Chemistry and Chemical Reactivity

John C. Kotz, Paul M. Treichel, John R. Townsend

Chapter 4

Stoichiometry: Quantitative Information About Chemical Reactions - all with Video Answers

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Chapter Questions

Problem 1

In a reaction known as the thermite reaction, iron(III) oxide reacts with aluminum to give molten iron.
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+2 \mathrm{Al}(\mathrm{s}) \rightarrow 2 \mathrm{Fe}(\ell)+\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{s})
$$
What amount of Al, in moles, is needed for complete reaction with 3.0 mol of $\mathrm{Fe}_{2} \mathrm{O}_{3} ?$ What mass of $\mathrm{Fe},$ in grams, can be produced?

Supratim Pal

Supratim Pal

Numerade Educator

Problem 2

What mass of HCl, in grams, is required to react with $0.750 \mathrm{g}$ of $\mathrm{Al}(\mathrm{OH})_{3} ?$ What mass of water, in grams, is produced?
$$
\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})+3 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{AlCl}_{3}(\mathrm{aq})+3 \mathrm{H}_{2} \mathrm{O}(\ell)
$$

Shveta Prithiani

Shveta Prithiani

Numerade Educator

Problem 3

Like many metals, aluminum reacts with a halogen to give a metal halide (page 99 ).
$$
2 \mathrm{Al}(\mathrm{s})+3 \mathrm{Br}_{2}(\ell) \rightarrow \mathrm{Al}_{2} \mathrm{Br}_{6}(\mathrm{s})
$$
What mass of $\mathrm{Br}_{2}$, in grams, is required for complete reaction with $2.56 \mathrm{g}$ of Al? What mass of white, solid $\mathrm{Al}_{2} \mathrm{Br}_{6}$ is expected?

Supratim Pal

Numerade Educator

Problem 4

The balanced equation for the reduction of iron ore to the metal using CO is
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+3 \mathrm{CO}(\mathrm{g}) \rightarrow 2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_{2}(\mathrm{g})
$$
(a) What is the maximum mass of iron, in grams, that can be obtained from $454 \mathrm{g}(1.00 \mathrm{lb})$ of iron(III) oxide?
(b) What mass of $\mathrm{CO}$ is required to react with $454 \mathrm{g}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3} ?$

Oluwapelumi Kolawole

Oluwapelumi Kolawole

Numerade Educator

Problem 5

Methane, $\mathrm{CH}_{4},$ burns in oxygen.
(a) What are the products of the reaction?
(b) Write the balanced equation for the reaction.
(c) What mass of $\mathrm{O}_{2}$, in grams, is required for complete combustion of $25.5 \mathrm{g}$ of methane?
(d) What is the total mass of products expected from the combustion of $25.5 \mathrm{g}$ of methane?

Shveta Prithiani

Shveta Prithiani

Numerade Educator

Problem 6

The formation of water-insoluble silver chloride is useful in the analysis of chloride-containing substances. Consider the following unbalanced equation:
$\mathrm{BaCl}_{2}(\mathrm{aq})+\mathrm{AgNO}_{3}(\mathrm{aq}) \rightarrow \mathrm{AgCl}(\mathrm{s})+\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})$
(a) Write the balanced equation.
(b) What mass of $\mathrm{AgNO}_{3},$ in grams, is required for complete reaction with $0.156 \mathrm{g}$ of $\mathrm{BaCl}_{2} ?$ What mass of AgCl is produced?

David Collins

Numerade Educator

Problem 7

For each question below, set up an amounts table that lists the initial amount or amounts of reactants, the changes in amounts of reactants and products, and the amounts of reactants and products after reaction (see page 140 and
Example $4.1)$.
The metals industry was a major source of air pollution years ago. One common process involved "roasting" metal sulfides in the air:
$$
2 \mathrm{PbS}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{PbO}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{g})
$$
If 2.50 mol of $\mathrm{PbS}$ is heated in air, what amount of $\mathrm{O}_{2}$ is required for complete reaction? What amounts of $\mathrm{PbO}$ and $\mathrm{SO}_{2}$ are expected?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 8

For each question below, set up an amounts table that lists the initial amount or amounts of reactants, the changes in amounts of reactants and products, and the amounts of reactants and products after reaction (see page 140 and
Example $4.1)$.
Iron ore is converted to iron metal in a reaction with carbon.
$$
2 \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+3 \mathrm{C}(\mathrm{s}) \rightarrow 4 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_{2}(\mathrm{g})
$$
If 6.2 mol of $\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})$ is used, what amount of $\mathrm{C}(\mathrm{s})$ is needed, and what amounts of Fe and $\mathrm{CO}_{2}$ are produced?

David Collins

Numerade Educator

Problem 9

For each question below, set up an amounts table that lists the initial amount or amounts of reactants, the changes in amounts of reactants and products, and the amounts of reactants and products after reaction (see page 140 and
Example $4.1)$.
Chromium metal reacts with oxygen to give chromium(III) oxide, $\mathrm{Cr}_{2} \mathrm{O}_{3}$
(a) Write a balanced equation for the reaction.
(b) What mass (in grams) of $\mathrm{Cr}_{2} \mathrm{O}_{3}$ is produced if
0.175 g of chromium metal is converted completely
to the oxide?
(c) What mass of $\mathrm{O}_{2}$ (in grams) is required for the reaction?

David Collins

Numerade Educator

Problem 9

Chromium metal reacts with oxygen to give chromium(III) oxide, $\mathrm{Cr}_{2} \mathrm{O}_{3}$.
(a) Write a balanced equation for the reaction.
(b) What mass (in grams) of $\mathrm{Cr}_{2} \mathrm{O}_{3}$ is produced if $0.175 \mathrm{g}$ of chromium metal is converted completely to the oxide?
(c) What mass of $\mathrm{O}_{2}$ (in grams) is required for the reaction?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 10

For each question below, set up an amounts table that lists the initial amount or amounts of reactants, the changes in amounts of reactants and products, and the amounts of reactants and products after reaction (see page 140 and
Example $4.1)$.
Ethane, $\mathrm{C}_{2} \mathrm{H}_{6},$ burns in oxygen.
(a) What are the products of the reaction?
(b) Write the balanced equation for the reaction.
(c) What mass of $\mathrm{O}_{2}$, in grams, is required for complete combustion of 13.6 of ethane?
(d) What is the total mass of products expected from the combustion of 13.6 g of ethane?

David Collins

Numerade Educator

Problem 11

Sodium sulfide, $\mathrm{Na}_{2} \mathrm{S},$ is used in the leather industry to remove hair from hides. The $\mathrm{Na}_{2} \mathrm{S}$ is made by the reaction
$$
\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{s})+4 \mathrm{C}(\mathrm{s}) \rightarrow \mathrm{Na}_{2} \mathrm{S}(\mathrm{s})+4 \mathrm{CO}(\mathrm{g})
$$
Suppose you mix $15 \mathrm{g}$ of $\mathrm{Na}_{2} \mathrm{SO}_{4}$ and $7.5 \mathrm{g}$ of $\mathrm{C}$ Which is the limiting reactant? What mass of $\mathrm{Na}_{2} \mathrm{S}$ is produced?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 12

Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with ammonium chloride.
$\mathrm{CaO}(\mathrm{s})+2 \mathrm{NH}_{4} \mathrm{Cl}(\mathrm{s}) \rightarrow$
$$
2 \mathrm{NH}_{3}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})+\mathrm{CaCl}_{2}(\mathrm{s})
$$
If 112 g of $\mathrm{CaO}$ and $224 \mathrm{g}$ of $\mathrm{NH}_{4} \mathrm{Cl}$ are mixed, what is the limiting reactant, and what mass of $\mathrm{NH}_{3}$ can be produced?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 13

The compound $\mathrm{SF}_{6}$ is made by burning sulfur in an atmosphere of fluorine. The balanced equation is
$$
\mathrm{S}_{8}(\mathrm{s})+24 \mathrm{F}_{2}(\mathrm{g}) \rightarrow 8 \mathrm{SF}_{6}(\mathrm{g})
$$
Starting with a mixture of 1.6 mol of sulfur, $S_{8},$ and
35 mol of $\mathrm{F}_{2}$
(a) Which is the limiting reagent?
(b) What amount of $\mathrm{SF}_{6}$ is produced?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 14

Disulfur dichloride, $S_{2} \mathrm{Cl}_{2}$, is used to vulcanize rubber. It can be made by treating molten sulfur with gaseous chlorine:
$$
\mathrm{S}_{8}(\ell)+4 \mathrm{Cl}_{2}(\mathrm{g}) \rightarrow 4 \mathrm{S}_{2} \mathrm{Cl}_{2}(\ell)
$$
Starting with a mixture of $32.0 \mathrm{g}$ of sulfur and $71.0 \mathrm{g}$ of $\mathrm{Cl}_{2}$
(a) Which is the limiting reactant?
(b) What is the theoretical yield of $S_{2} C l_{2} ?$
(c) What mass of the excess reactant remains when the reaction is completed?

Thomas Harr

Numerade Educator

Problem 15

The reaction of methane and water is one way to prepare hydrogen for use as a fuel:
$$
\mathrm{CH}_{4}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightarrow \mathrm{CO}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g})
$$
If you begin with $995 \mathrm{g}$ of $\mathrm{CH}_{4}$ and $2510 \mathrm{g}$ of water,
(a) Which reactant is the limiting reactant?
(b) What is the maximum mass of $\mathrm{H}_{2}$ that can be prepared?
(c) What mass of the excess reactant remains when the reaction is completed?

Jacquelin Ho

Numerade Educator

Problem 16

Aluminum chloride, AlCl $_{3}$, is made by treating scrap aluminum with chlorine.
$$
2 \mathrm{Al}(\mathrm{s})+3 \mathrm{Cl}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{AlCl}_{3}(\mathrm{s})
$$
If you begin with $2.70 \mathrm{g}$ of $\mathrm{Al}$ and $4.05 \mathrm{g}$ of $\mathrm{Cl}_{2}$
(a) Which reactant is limiting?
(b) What mass of $\mathrm{AlCl}_{3}$ can be produced?
(c) What mass of the excess reactant remains when the reaction is completed?
(d) Set up an amounts table for this problem.

Ronald Prasad

Numerade Educator

Problem 17

In the thermite reaction, iron(III) oxide is reduced by aluminum to give molten iron.
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+2 \mathrm{Al}(\mathrm{s}) \rightarrow 2 \mathrm{Fe}(\ell)+\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{s})
$$
If you begin with $10.0 \mathrm{g}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ and $20.0 \mathrm{g}$ of $\mathrm{Al}$
(a) Which reactant is limiting?
(b) What mass of Fe can be produced?
(c) What mass of the excess reactant remains after the limiting reactant is consumed?
(d) Set up an amounts table for this problem.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 18

Aspirin, $\mathrm{C}_{6} \mathrm{H}_{4}\left(\mathrm{OCOCH}_{3}\right) \mathrm{CO}_{2} \mathrm{H}$, is produced by the
reaction of salicylic acid, $\mathrm{C}_{6} \mathrm{H}_{4}(\mathrm{OH}) \mathrm{CO}_{2} \mathrm{H}$, and acetic anhydride, $\left(\mathrm{CH}_{3} \mathrm{CO}\right)_{2} \mathrm{O}$ (page 149).
$$\begin{array}{l}
\mathrm{C}_{6} \mathrm{H}_{4}(\mathrm{OH}) \mathrm{CO}_{2} \mathrm{H}(\mathrm{s})+\left(\mathrm{CH}_{3} \mathrm{CO}\right)_{2} \mathrm{O}(\ell) \rightarrow \\
\mathrm{C}_{6} \mathrm{H}_{4}\left(\mathrm{OCOCH}_{3}\right) \mathrm{CO}_{2} \mathrm{H}(\mathrm{s})+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(\ell)
\end{array}$$
If you mix $100 . \mathrm{g}$ of each of the reactants, what is the maximum mass of aspirin that can be obtained?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 19

In Example $4.2,$ you found that a particular mixture of CO and $\mathrm{H}_{2}$ could produce $407 \mathrm{g} \mathrm{CH}_{3} \mathrm{OH}$.
$$
\mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{g}) \rightarrow \mathrm{CH}_{3} \mathrm{OH}(\ell)
$$
If only 332 g of $\mathrm{CH}_{3} \mathrm{OH}$ is actually produced, what is the percent yield of the compound?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 20

Ammonia gas can be prepared by the following reaction:
$\mathrm{CaO}(\mathrm{s})+2 \mathrm{NH}_{4} \mathrm{Cl}(\mathrm{s}) \rightarrow$
$$
2 \mathrm{NH}_{3}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})+\mathrm{CaCl}_{2}(\mathrm{s})
$$
If 112 g of $\mathrm{CaO}$ and $224 \mathrm{g}$ of $\mathrm{NH}_{4} \mathrm{Cl}$ are mixed, the theoretical yield of $\mathrm{NH}_{3}$ is $68.0 \mathrm{g}$ (Study Question 12 ). If only $16.3 \mathrm{g}$ of $\mathrm{NH}_{3}$ is actually obtained, what is its percent yield?

Ronald Prasad

Numerade Educator

Problem 21

The deep blue compound $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4}$ is made by the reaction of copper(II) sulfate and ammonia.
$$
\mathrm{CuSO}_{4}(\mathrm{aq})+4 \mathrm{NH}_{3}(\mathrm{aq}) \rightarrow \mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4}(\mathrm{aq})
$$
(a) If you use $10.0 \mathrm{g}$ of $\mathrm{CuSO}_{4}$ and excess $\mathrm{NH}_{3},$ what is the theoretical yield of $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4} ?$
(b) If you isolate $12.6 \mathrm{g}$ of $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4},$ what is the percent yield of $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4} ?$

Jacquelin Ho

Numerade Educator

Problem 22

Black smokers are found in the depths of the oceans (page $96) .$ Thinking that the conditions in these smokers might be conducive to the formation of organic compounds, two chemists in Germany found the following reaction could occur in similar conditions.
$$
2 \mathrm{CH}_{3} \mathrm{SH}+\mathrm{CO} \rightarrow \mathrm{CH}_{3} \mathrm{COSCH}_{3}+\mathrm{H}_{2} \mathrm{S}
$$
If you begin with $10.0 \mathrm{g}$ of $\mathrm{CH}_{3} \mathrm{SH}$ and excess $\mathrm{CO}$
(a) What is the theoretical yield of $\mathrm{CH}_{3} \mathrm{COSCH}_{3} ?$
(b) If $8.65 \mathrm{g}$ of $\mathrm{CH}_{3} \mathrm{COSCH}_{3}$ is isolated, what is its percent yield?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 23

The reaction of methane and water is one way to prepare hydrogen for use as a fuel:
$$
\mathrm{CH}_{4}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightarrow \mathrm{CO}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g})
$$
Under certain conditions, what mass of $\mathrm{CH}_{4}$ is required to produce $15 \mathrm{g}$ of $\mathrm{H}_{2}$ if this reaction has a $37 \%$ yield?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 24

Methanol, $\mathrm{CH}_{3} \mathrm{OH},$ can be made from the reaction of carbon monoxide and hydrogen.
$$
\mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{g}) \rightarrow \mathrm{CH}_{3} \mathrm{OH}(\ell)
$$
What mass of hydrogen is required to produce $1.0 \mathrm{L}$ of $\mathrm{CH}_{3} \mathrm{OH}(d=0.791 \mathrm{g} / \mathrm{mL})$ if this reaction has a $74 \%$
yield under certain conditions?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 25

A mixture of $\mathrm{CuSO}_{4}$ and $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ has a mass of $1.245 \mathrm{g} .$ After heating to drive off all the water, the mass is only $0.832 \mathrm{g} .$ What is the mass percent of $\left.\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} \text { in the mixture? (See page } 89 .\right)$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 26

A 2.634 -g sample containing impure $\mathrm{CuCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ was heated. The sample mass after heating to drive off the water was $2.125 \mathrm{g} .$ What was the mass percent of $\mathrm{CuCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ in the original sample?

Ronald Prasad

Numerade Educator

Problem 27

A sample of limestone and other soil materials was heated, and the limestone decomposed to give calcium oxide and carbon dioxide.
$$
\mathrm{CaCO}_{3}(\mathrm{s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})
$$
A 1.506 -g sample of limestone-containing material gave $0.558 \mathrm{g}$ of $\mathrm{CO}_{2},$ in addition to $\mathrm{CaO},$ after being heated at a high temperature. What was the mass percent of $\mathrm{CaCO}_{3}$ in the original sample?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 28

At higher temperatures, $\mathrm{NaHCO}_{3}$ is converted quantitatively to $\mathrm{Na}_{2} \mathrm{CO}_{3}$
$$
2 \mathrm{NaHCO}_{3}(\mathrm{s}) \rightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})
$$
Heating a 1.7184 -g sample of impure $\mathrm{NaHCO}_{3}$ gives $0.196 \mathrm{g}$ of $\mathrm{CO}_{2} .$ What was the mass percent of $\mathrm{NaHCO}_{3}$ in the original 1.7184 -g sample?

Ronald Prasad

Numerade Educator

Problem 29

Nickel(II) sulfide, NiS, occurs naturally as the relatively rare mineral millerite. One of its occurrences is in meteorites. To analyze a mineral sample for the quantity of NiS, the sample is dissolved in nitric acid to form a solution of $\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}$
$\mathrm{NiS}(\mathrm{s})+4 \mathrm{HNO}_{3}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NO}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{S}(\mathrm{s})
$$
The aqueous solution of $\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}$ is then reacted with the organic compound dimethylglyoxime $\left(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{N}_{2} \mathrm{O}_{2}\right)$ to give the red solid $\mathrm{Ni}\left(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{N}_{2} \mathrm{O}_{2}\right)_{2}$
$\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{C}_{4} \mathrm{H}_{8} \mathrm{N}_{2} \mathrm{O}_{2}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Ni}\left(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{N}_{2} \mathrm{O}_{2}\right)_{2}(\mathrm{s})+2 \mathrm{HNO}_{3}(\mathrm{aq})
$$
Suppose a 0.468 -g sample containing millerite produces $0.206 \mathrm{g}$ of red, solid $\mathrm{Ni}\left(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{N}_{2} \mathrm{O}_{2}\right)_{2} .$ What is the mass
percent of NiS in the sample?

Ronald Prasad

Numerade Educator

Problem 30

The aluminum in a 0.764 -g sample of an unknown material was precipitated as aluminum hydroxide, $\mathrm{Al}(\mathrm{OH})_{3},$ which was then converted to $\mathrm{Al}_{2} \mathrm{O}_{3}$ by heating strongly. If $0.127 \mathrm{g}$ of $\mathrm{Al}_{2} \mathrm{O}_{3}$ is obtained from the 0.764 -g sample, what is the mass percent of aluminum in the sample?

David Collins

Numerade Educator

Problem 31

Styrene, the building block of polystyrene, consists of only $\mathrm{C}$ and $\mathrm{H}$. If $0.438 \mathrm{g}$ of styrene is burned in oxygen and produces $1.481 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.303 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ what is the empirical formula of styrene?

Jacquelin Ho

Numerade Educator

Problem 32

Mesitylene is a liquid hydrocarbon. Burning $0.115 \mathrm{g}$ of the compound in oxygen gives $0.379 \mathrm{g}$ of $\mathrm{CO}_{2}$ and
$0.1035 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} .$ What is the empirical formula of mesitylene?

David Collins

Numerade Educator

Problem 33

Naphthalene is a hydrocarbon that once was used in mothballs. If $0.3093 \mathrm{g}$ of the compound is burned in oxygen, $1.0620 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.1739 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ are isolated.
(a) What is the empirical formula of naphthalene?
(b) If a separate experiment gave $128.2 \mathrm{g} / \mathrm{mol}$ as the molar mass of the compound, what is its molecular formula?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 34

Azulene is a beautiful blue hydrocarbon. If $0.106 \mathrm{g}$ of the compound is burned in oxygen, $0.364 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.0596 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ are isolated.
(a) What is the empirical formula of azulene?
(b) If a separate experiment gave $128.2 \mathrm{g} / \mathrm{mol}$ as the molar mass of the compound, what is its molecular formula?

David Collins

Numerade Educator

Problem 35

An unknown compound has the formula $\mathrm{C}_{x} \mathrm{H}_{y} \mathrm{O}_{z} .$ You burn 0.0956 g of the compound and isolate $0.1356 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.0833 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} .$ What is the empirical formula of the compound? If the molar mass is $62.1 \mathrm{g} / \mathrm{mol},$ what is the molecular formula?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 36

An unknown compound has the formula $\mathrm{C}_{x} \mathrm{H}_{y} \mathrm{O}_{z} .$ You burn $0.1523 \mathrm{g}$ of the compound and isolate $0.3718 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.1522 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} .$ What is the empirical formula of the compound? If the molar mass is 72.1 g/mol, what is the molecular formula?

Ronald Prasad

Numerade Educator

Problem 37

Nickel forms a compound with carbon monoxide, $\mathrm{Ni}_{x}(\mathrm{CO})_{y} .$ To determine its formula, you carefully heat a 0.0973 -g sample in air to convert the nickel to $0.0426 \mathrm{g}$ of $\mathrm{NiO}$ and the $\mathrm{CO}$ to $0.100 \mathrm{g}$ of $\mathrm{CO}_{2} .$ What is the empirical formula of $\mathrm{Ni}_{x}(\mathrm{CO})_{y} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 38

To find the formula of a compound composed of iron and carbon monoxide, $\mathrm{Fe}_{x}(\mathrm{CO})_{y},$ the compound is burned in pure oxygen to give $\mathrm{Fe}_{2} \mathrm{O}_{3}$ and $\mathrm{CO}_{2} .$ If you burn $1.959 \mathrm{g}$ of $\mathrm{Fe}_{x}(\mathrm{CO})_{y}$ and obtain $0.799 \mathrm{g}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3}$
and $2.200 \mathrm{g}$ of $\mathrm{CO}_{2},$ what is the empirical formula of $\mathrm{Fe}_{x}(\mathrm{CO})_{y} ?$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 39

If $6.73 \mathrm{g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ is dissolved in enough water to make $250 .$ mL of solution, what is the molar concentration of the sodium carbonate? What are the molar concentrations of the $\mathrm{Na}^{+}$ and $\mathrm{CO}_{3}^{2-}$ ions?

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 40

Some potassium dichromate $\left(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\right), 2.335 \mathrm{g},$ is dissolved in enough water to make exactly $500 .$ mL of solution. What is the molar concentration of the potassium dichromate? What are the molar concentrations of the $\mathrm{K}^{+}$ and $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$ ions?

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 41

What is the mass of solute, in grams, in $250 .$ mL of a $0.0125 \mathrm{M}$ solution of $\mathrm{KMnO}_{4} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 42

What is the mass of solute, in grams, in 125 mL of a $1.023 \times 10^{-3} \mathrm{M}$ solution of $\mathrm{Na}_{3} \mathrm{PO}_{4} ?$ What is the
molar concentration of the $\mathrm{Na}^{+}$ and $\mathrm{PO}_{4}^{3-}$ ion?

Ronald Prasad

Numerade Educator

Problem 43

What volume of $0.123 \mathrm{M} \mathrm{NaOH},$ in milliliters, contains $25.0 \mathrm{g}$ of $\mathrm{NaOH} ?$

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 44

What volume of $2.06 \mathrm{M} \mathrm{KMnO}_{4},$ in liters, contains
322 g of solute?

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 45

Identify the ions that exist in each aqueous solution, and specify the concentration of each ion.
(a) $0.25 \mathrm{M}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$
(b) $0.123 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$
(c) $0.056 \mathrm{M} \mathrm{HNO}_{3}$

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 46

Identify the ions that exist in each aqueous solution, and specify the concentration of each ion.
(a) $0.12 \mathrm{M} \mathrm{BaCl}_{2}$
(b) $0.0125 \mathrm{M} \mathrm{CuSO}_{4}$
(c) $0.500 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 47

An experiment in your laboratory requires $500 .$ mL of a $0.0200 \mathrm{M}$ solution of $\mathrm{Na}_{2} \mathrm{CO}_{3} .$ You are given solid $\mathrm{Na}_{2} \mathrm{CO}_{3},$ distilled water, and a $500 .$ -mL volumetric flask. Describe how to prepare the required solution.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 48

What mass of oxalic acid, $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},$ is required to prepare $250 .$ mL of a solution that has a concentration of $0.15 \mathrm{M} \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} ?$

Ronald Prasad

Numerade Educator

Problem 49

If you dilute $25.0 \mathrm{mL}$ of $1.50 \mathrm{M}$ hydrochloric acid to $500 . \mathrm{mL},$ what is the molar concentration of the dilute acid?

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 50

If $4.00 \mathrm{mL}$ of $0.0250 \mathrm{M} \mathrm{CuSO}_{4}$ is diluted to $10.0 \mathrm{mL}$
with pure water, what is the molar concentration of copper(II) sulfate in the diluted solution?

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 51

Which of the following methods would you use to prepare $1.00 \mathrm{L}$ of $0.125 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} ?$
(a) Dilute $20.8 \mathrm{mL}$ of $6.00 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ to a volume of $1.00 \mathrm{L}$
(b) Add $950 .$ mL of water to 50.0 mL of $3.00 \mathrm{M}$ $\mathrm{H}_{2} \mathrm{SO}_{4}$.

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 52

Which of the following methods would you use to prepare $300 .$ mL of $0.500 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} ?$
(a) Add $30.0 \mathrm{mL}$ of $1.50 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ to $270 .$ mL of
water.
(b) Dilute $250 .$ mL of $0.600 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ to a volume of
$300 . \mathrm{mL}$.

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 53

You have $250 .$ mL of $0.136 \mathrm{M}$ HCl. Using a volumetric pipet, you take $25.00 \mathrm{mL}$ of that solution and dilute it to $100.00 \mathrm{mL}$ in a volumetric flask. Now you take $10.00 \mathrm{mL}$ of that solution, using a volumetric pipet, and dilute it to $100.00 \mathrm{mL}$ in a volumetric flask. What is the concentration of hydrochloric acid in the final solution?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 54

Suppose you have $100.00 \mathrm{mL}$ of a solution of a dye and transfer $2.00 \mathrm{mL}$ of the solution to a $100.00-\mathrm{mL}$ volumetric flask. After adding water to the $100.00 \mathrm{mL}$ mark, you take 5.00 mL of that solution and again dilute to $100.00 \mathrm{mL} .$ If you find the dye concentration in the final diluted sample is $0.000158 \mathrm{M},$ what was the dye concentration in the original solution?

Ronald Prasad

Numerade Educator

Problem 55

A table wine has a pH of $3.40 .$ What is the hydronium ion concentration of the wine? Is it acidic or basic?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 56

A saturated solution of milk of magnesia, $\mathrm{Mg}(\mathrm{OH})_{2}$ has a pH of $10.5 .$ What is the hydronium ion concentration of the solution? Is the solution acidic or basic?

Ronald Prasad

Numerade Educator

Problem 57

What is the hydronium ion concentration of a $0.0013 \mathrm{M}$ solution of HNO $_{3} ?$ What is its pH?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 58

What is the hydronium ion concentration of a $1.2 \times 10^{-4} \mathrm{M}$ solution of $\mathrm{HClO}_{4} ?$ What is its $\mathrm{pH} ?$

Ronald Prasad

Numerade Educator

Problem 59

Make the following conversions. In each case, tell whether the solution is acidic or basic.

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 60

Make the following conversions. In each case, tell whether the solution is acidic or basic.

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 61

What volume of $0.109 \mathrm{M} \mathrm{HNO}_{3},$ in milliliters, is required to react completely with $2.50 \mathrm{g}$ of $\mathrm{Ba}(\mathrm{OH})_{2} ?$ $2 \mathrm{HNO}_{3}(\mathrm{aq})+\mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{s}) \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})$

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 62

What mass of $\mathrm{Na}_{2} \mathrm{CO}_{3},$ in grams, is required for complete reaction with $50.0 \mathrm{mL}$ of $0.125 \mathrm{M} \mathrm{HNO}_{3} ?$
$\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})+2 \mathrm{HNO}_{3}(\mathrm{aq}) \rightarrow$
$$
2 \mathrm{NaNO}_{3}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 63

When an electric current is passed through an aqueous solution of $\mathrm{NaCl}$, the valuable industrial chemicals $\mathrm{H}_{2}(\mathrm{g}), \mathrm{Cl}_{2}(\mathrm{g}),$ and $\mathrm{NaOH}$ are produced.
$2 \mathrm{NaCl}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow$
$$
\mathrm{H}_{2}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{g})+2 \mathrm{NaOH}(\mathrm{aq})
$$
What mass of NaOH can be formed from $15.0 \mathrm{L}$ of $0.35 \mathrm{M} \mathrm{NaCl} ?$ What mass of chlorine is obtained?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 64

Hydrazine, $\mathrm{N}_{2} \mathrm{H}_{4},$ a base like ammonia, can react with sulfuric acid.
$2 \mathrm{N}_{2} \mathrm{H}_{4}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow 2 \mathrm{N}_{2} \mathrm{H}_{5}^{+}(\mathrm{aq})+\mathrm{SO}_{4}^{2-}(\mathrm{aq})$
What mass of hydrazine reacts with $250 .$ mL of $0.146 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} ?$

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 65

In the photographic developing process, silver bromide is dissolved by adding sodium thiosulfate. $\mathrm{AgBr}(\mathrm{s})+2 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NaBr}(\mathrm{aq})
$$
If you want to dissolve $0.225 \mathrm{g}$ of AgBr, what volume
of $0.0138 \mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3},$ in milliliters, should be used?
(a) A precipitate of AgBr formed by adding $\mathrm{AgNO}_{3}(\mathrm{aq})$ to $\mathrm{KBr}(\mathrm{aq}) .$ (b) On adding $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq})$
sodium thiosulfate, the solid AgBr dissolves.

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 65

In the photographic developing process, silver bromide is dissolved by adding sodium thiosulfate.
\[\begin{aligned}
\operatorname{AgBr}(s)+2 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq}) & \rightarrow \\
\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NaBr}(\mathrm{aq})
\end{aligned}\]
If you want to dissolve $0.225 \mathrm{g}$ of $\mathrm{AgBr}$, what volume of $0.0138 \mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3},$ in milliliters, should be used?
(a) A precipitate of AgBr formed by adding $\mathrm{AgNO}_{3}(\mathrm{aq})$ to $\mathrm{KBr}(\mathrm{aq}) .$ (b) On adding $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq})$ sodium thiosulfate, the solid AgBr dissolves.

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 66

You can dissolve an aluminum soft drink can in an aqueous base such as potassium hydroxide.
$$
\begin{aligned}
2 \mathrm{Al}(\mathrm{s})+2 \mathrm{KOH}(\mathrm{aq})+6 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow & \\
2 \mathrm{KAl}(\mathrm{OH})_{4}(\mathrm{aq})+3 \mathrm{H}_{2}(\mathrm{g})
\end{aligned}
$$
If you place $2.05 \mathrm{g}$ of aluminum in a beaker with $185 \mathrm{mL}$ of $1.35 \mathrm{M} \mathrm{KOH},$ will any aluminum remain? What mass of $\mathrm{KAl}(\mathrm{OH})_{4}$ is produced?

Ronald Prasad

Numerade Educator

Problem 67

What volume of $0.750 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2},$ in milliliters, is required to react completely with $1.00 \mathrm{L}$ of $2.25 \mathrm{M}$ NaCl solution? The balanced equation is $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NaCl}(\mathrm{aq}) \rightarrow \mathrm{PbCl}_{2}(\mathrm{s})+2 \mathrm{NaNO}_{3}(\mathrm{aq})$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 68

What volume of $0.125 \mathrm{M}$ oxalic acid, $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},$ is required to react with $35.2 \mathrm{mL}$ of $0.546 \mathrm{M} \mathrm{NaOH} ?$
$\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)
$$

Ronald Prasad

Numerade Educator

Problem 69

What volume of $0.812 \mathrm{M} \mathrm{HCl}$, in milliliters, is required to titrate $1.45 \mathrm{g}$ of $\mathrm{NaOH}$ to the equivalence point?
$$
\mathrm{NaOH}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{NaCl}(\mathrm{aq})
$$

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 70

What volume of $0.955 \mathrm{M} \mathrm{HCl},$ in milliliters, is required to titrate $2.152 \mathrm{g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ to the equivalence point?
$\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow$
$$
\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{NaCl}(\mathrm{aq})
$$

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 71

If $38.55 \mathrm{mL}$ of $\mathrm{HCl}$ is required to titrate $2.150 \mathrm{g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ according to the following equation, what is the concentration $(\mathrm{mol} / \mathrm{L})$ of the HCl solution?
$\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq}) \mp 2 \mathrm{HCl}(\mathrm{aq}) \rightarrow$
$$
2 \mathrm{NaCl}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 72

Potassium hydrogen phthalate, $\mathrm{KHC}_{8} \mathrm{H}_{4} \mathrm{O}_{4},$ is used to standardize solutions of bases. The acidic anion reacts with strong bases according to the following net ionic equation:
$\mathrm{HC}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{-}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \rightarrow \mathrm{C}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
If a 0.902 -g sample of potassium hydrogen phthalate is dissolved in water and titrated to the equivalence point with $26.45 \mathrm{mL}$ of $\mathrm{NaOH}(\mathrm{aq}),$ what is the molar concentration of the NaOH?

Michelle Neer

Numerade Educator

Problem 73

You have $0.954 \mathrm{g}$ of an unknown acid, $\mathrm{H}_{2} \mathrm{A},$ which reacts with NaOH according to the balanced equation
$$
\mathrm{H}_{2} \mathrm{A}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow \mathrm{Na}_{2} \mathrm{A}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)
$$
If $36.04 \mathrm{mL}$ of $0.509 \mathrm{M} \mathrm{NaOH}$ is required to titrate the acid to the second equivalence point, what is the molar mass of the acid?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 74

An unknown solid acid is either citric acid or tartaric acid. To determine which acid you have, you titrate a sample of the solid with aqueous $\mathrm{NaOH}$ and from this determine the molar mass of the unknown acid. The appropriate equations are as follows:
Citric acid:
$$
\begin{aligned}
\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{NaOH}(\mathrm{aq}) & \rightarrow \\
3 \mathrm{H}_{2} \mathrm{O}(\ell) &+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})
\end{aligned}
$$
Tartaric acid:
$\mathrm{H}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow$
$$
2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{Na}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}(\mathrm{aq})
$$
A 0.956 -g sample requires $29.1 \mathrm{mL}$ of $0.513 \mathrm{M} \mathrm{NaOH}$ to consume the acid completely. What is the unknown acid?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 75

To analyze an iron-containing compound, you convert all the iron to $\mathrm{Fe}^{2+}$ in aqueous solution and then titrate the solution with standardized KMnO $_{4} .$ The balanced, net ionic equation is $\mathrm{MnO}_{4}^{-}(\mathrm{aq})+5 \mathrm{Fe}^{2+}(\mathrm{aq})+8 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Mn}^{2+}(\mathrm{aq})+5 \mathrm{Fe}^{3+}(\mathrm{aq})+12 \mathrm{H}_{2} \mathrm{O}(\ell)
$$
A 0.598 -g sample of the iron-containing compound requires $22.25 \mathrm{mL}$ of $0.0123 \mathrm{M} \mathrm{KMnO}_{4}$ for titration to the equivalence point. What is the mass percent of iron in the sample?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 76

Vitamin C has the formula $\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6} .$ Besides being an acid, it is a reducing agent. One method for determining the amount of vitamin C in a sample is to titrate it with a solution of bromine, $\mathrm{Br}_{2},$ an oxidizing agent.
$$
\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{Br}_{2}(\mathrm{aq}) \rightarrow 2 \mathrm{HBr}(\mathrm{aq})+\mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{6}(\mathrm{aq})
$$ A 1.00 -g "chewable" vitamin C tablet requires $27.85 \mathrm{mL}$ of $0.102 \mathrm{M} \mathrm{Br}_{2}$ for titration to the equivalence point. What is the mass of vitamin C in the tablet?

Ronald Prasad

Numerade Educator

Problem 77

(See Section $4-8$ and Example $4.14 .$ The problems below are adapted from Fundamentals of Analytical Chemistry, $8 t b$ ed. by D. A. Skoog, D. M. West, F.J. Holler, and S. R. Crouch, Thomson/Brooks-Cole, Belmont, CA $2004 .)$
A solution of a dye was analyzed by spectrophotometry, and the following calibration data were collected.
(a) Construct a calibration plot, and determine the slope and intercept.
(b) What is the dye concentration in a solution with $A=0.52 ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 78

(See Section $4-8$ and Example $4.14 .$ The problems below are adapted from Fundamentals of Analytical Chemistry, $8 t b$ ed. by D. A. Skoog, D. M. West, F.J. Holler, and S. R. Crouch, Thomson/Brooks-Cole, Belmont, CA $2004 .)$
The nitrite ion is involved in the biochemical nitrogen cycle. You can determine the nitrite ion content of a sample using spectrophotometry by first using several organic compounds to form a colored compound from the ion. The following data were collected.
(a) Construct a calibration plot, and determine the slope and intercept.
(b) What is the nitrite ion concentration in the unknown solution?

Ronald Prasad

Numerade Educator

Problem 79

Suppose $16.04 \mathrm{g}$ of benzene, $\mathrm{C}_{6} \mathrm{H}_{6},$ is burned in oxygen.
(a) What are the products of the reaction?
(b) Write a balanced equation for the reaction.
(c) What mass of $\mathrm{O}_{2}$, in grams, is required for complete combustion of benzene?
(d) What is the total mass of products expected from the combustion of $16.04 \mathrm{g}$ of benzene?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 80

The metabolic disorder diabetes causes a buildup of acetone, $\mathrm{CH}_{3} \mathrm{COCH}_{3},$ in the blood. Acetone, a volatile compound, is exhaled, giving the breath of untreated diabetics a distinctive odor. The acetone is produced by a breakdown of fats in a series of reactions. The equation for the last step, the breakdown of acetoacetic acid to give acetone and $\mathrm{CO}_{2},$ is
$$\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CO}_{2} \mathrm{H} \rightarrow \mathrm{CH}_{3} \mathrm{COCH}_{3}+\mathrm{CO}_{2}$$
What mass of acetone can be produced from 125 mg of acetoacetic acid?

Ronald Prasad

Numerade Educator

Problem 81

Your body deals with excess nitrogen by excreting it in the form of urea, $\mathrm{NH}_{2} \mathrm{CONH}_{2} .$ The reaction producing it is the combination of arginine $\left(\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{N}_{4} \mathrm{O}_{2}\right)$ with water to give urea and ornithine $\left(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{N}_{2} \mathrm{O}_{2}\right)$
$$\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{N}_{4} \mathrm{O}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{2} \mathrm{CONH}_{2}+\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{N}_{2} \mathrm{O}_{2}$$
If you excrete 95 mg of urea, what mass of arginine must have been used? What mass of ornithine must have been produced?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 82

The reaction of iron metal and chlorine gas to give iron(III) chloride is illustrated below.
(a) Write the balanced chemical equation for the reaction.
(b) Beginning with $10.0 \mathrm{g}$ of iron, what mass of $\mathrm{Cl}_{2},$ in grams, is required for complete reaction? What mass of $\mathrm{FeCl}_{3}$ can be produced?
(c) If only $18.5 \mathrm{g}$ of $\mathrm{FeCl}_{3}$ is obtained from $10.0 \mathrm{g}$ of iron and excess $\mathrm{Cl}_{2}$, what is the percent yield?
(d) If $10.0 \mathrm{g}$ each of iron and chlorine are combined, what is the theoretical yield of iron(III) chloride?

Ronald Prasad

Numerade Educator

Problem 83

Some metal halides react with water to produce the metal oxide and the appropriate hydrogen halide (see photo). For example,
$$
\mathrm{TiCl}_{4}(\ell)+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{TiO}_{2}(\mathrm{s})+4 \mathrm{HCl}(\mathrm{g})
$$
(a) Name the four compounds involved in this reaction.
(b) If you begin with 14.0 mL of $\mathrm{TiCl}_{4}(d=1.73 \mathrm{g} / \mathrm{mL})$ what mass of water, in grams, is required for complete reaction?
(c) What mass of each product is expected?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 84

The reaction of $750 .$ g each of $\mathrm{NH}_{3}$ and $\mathrm{O}_{2}$ was found to produce $562 \mathrm{g}$ of $\mathrm{NO}$ (see pages $144-145$ ).
$$
4 \mathrm{NH}_{3}(\mathrm{g})+5 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\ell)
$$
(a) What mass of water is produced by this reaction?
(b) What mass of $\mathrm{O}_{2}$ is required to consume $750 .$ g of $\mathrm{NH}_{3} ?$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 85

Sodium azide, an explosive chemical used in automobile airbags, is made by the following reaction:
$$
\mathrm{NaNO}_{3}+3 \mathrm{NaNH}_{2} \rightarrow \mathrm{NaN}_{3}+3 \mathrm{NaOH}+\mathrm{NH}_{3}
$$
If you combine $15.0 \mathrm{g}$ of $\mathrm{NaNO}_{3}$ with $15.0 \mathrm{g}$ of $\mathrm{NaNH}_{2},$ what mass of $\mathrm{NaN}_{3}$ is produced?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 86

Iodine is made by the following reaction
$2 \mathrm{NaIO}_{3}(\mathrm{aq})+5 \mathrm{NaHSO}_{3}(\mathrm{aq}) \rightarrow$
$$
3 \mathrm{NaHSO}_{4}(\mathrm{aq})+2 \mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{I}_{2}(\mathrm{aq})
$$
(a) Name the two reactants.
(b) If you wish to prepare $1.00 \mathrm{kg}$ of $\mathrm{I}_{2},$ what masses of $\mathrm{NaIO}_{3}$ and $\mathrm{NaHSO}_{3}$ are required?
(c) What is the theoretical yield of $I_{2}$ if you mixed $15.0 \mathrm{g}$ of $\mathrm{NaIO}_{3}$ with $125 \mathrm{mL}$ of $0.853 \mathrm{M}$
$\mathrm{NaHSO}_{3} ?$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 87

Saccharin, an artificial sweetener, has the formula $\mathrm{C}_{7} \mathrm{H}_{5} \mathrm{NO}_{3} \mathrm{S} .$ Suppose you have a sample of a saccharincontaining sweetener with a mass of $0.2140 \mathrm{g}$. After decomposition to free the sulfur and convert it to the $\mathrm{SO}_{4}^{2-}$ ion, the sulfate ion is trapped as water-insoluble BaSO (Figure 4.4). The quantity of BaSO $_{4}$ obtained is $0.2070 \mathrm{g} .$ What is the mass percent of saccharin in the sample of sweetener?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 88

Boron forms a series of compounds with hydrogen, all with the general formula $\mathrm{B}_{x} \mathrm{H}_{y}$.
$$
\mathrm{B}_{x} \mathrm{H}_{y}(\mathrm{s})+\operatorname{excess} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \frac{x}{2} \mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{s})+\frac{y}{2} \mathrm{H}_{2} \mathrm{O}(\mathrm{g})
$$
If $0.148 \mathrm{g}$ of one of these compounds gives $0.422 \mathrm{g}$ of $\mathrm{B}_{2} \mathrm{O}_{3}$ when burned in excess $\mathrm{O}_{2},$ what is its empirical formula?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 89

Silicon and hydrogen form a series of compounds with the general formula $\mathrm{Si}_{x} \mathrm{H}_{y} .$ To find the formula of one of them, a 6.22 -g sample of the compound is burned in oxygen. All of the Si is converted to $11.64 \mathrm{g}$ of $\mathrm{SiO}_{2},$ and all of the $\mathrm{H}$ is converted to $6.980 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} .$ What is the empirical formula of the silicon compound?

David Collins

Numerade Educator

Problem 90

Menthol, from oil of mint, has a characteristic odor. The compound contains only $\mathrm{C}, \mathrm{H}$, and $\mathrm{O} .$ If $95.6 \mathrm{mg}$ of menthol burns completely in $\mathrm{O}_{2},$ and gives $269 \mathrm{mg}$ of $\mathrm{CO}_{2}$ and $111 \mathrm{mg}$ of $\mathrm{H}_{2} \mathrm{O},$ what is the empirical formula of menthol?

Ronald Prasad

Numerade Educator

Problem 91

Benzoquinone, a chemical used in the dye industry and in photography, is an organic compound containing only $\mathrm{C}, \mathrm{H},$ and $\mathrm{O} .$ What is the empirical formula of the compound if $0.105 \mathrm{g}$ of the compound gives $0.257 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $0.0350 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ when burned completely in oxygen?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 92

Aqueous solutions of iron(II) chloride and sodium sulfide react to form iron(II)sulfide and sodium chloride.
(a) Write the balanced equation for the reaction.
(b) If you combine $40 .$ g each of $\mathrm{Na}_{2} \mathrm{S}$ and $\mathrm{FeCl}_{2},$ what is the limiting reactant?
(c) What mass of FeS is produced?
(d) What mass of $\mathrm{Na}_{2} \mathrm{S}$ or $\mathrm{FeCl}_{2}$ remains after the reaction?
(e) What mass of $\mathrm{FeCl}_{2}$ is required to react completely with $40 . \mathrm{g}$ of $\mathrm{Na}_{2} \mathrm{S} ?$

Ronald Prasad

Numerade Educator

Problem 93

Sulfuric acid can be prepared starting with the sulfide ore, cuprite $\left(\mathrm{Cu}_{2} \mathrm{S}\right) .$ If each $\mathrm{S}$ atom in $\mathrm{Cu}_{2} \mathrm{S}$ leads to one molecule of $\mathrm{H}_{2} \mathrm{SO}_{4},$ what is the theoretical yield of $\mathrm{H}_{2} \mathrm{SO}_{4}$ from $3.00 \mathrm{kg}$ of $\mathrm{Cu}_{2} \mathrm{S} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 94

In an experiment, $1.056 \mathrm{g}$ of a metal carbonate, containing an unknown metal $\mathrm{M}$, is heated to give the metal oxide and $0.376 \mathrm{g} \mathrm{CO}_{2}$
$\mathrm{MCO}_{3}(\mathrm{s})+$ heat $\rightarrow \mathrm{MO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})$
What is the identity of the metal M?
(a) $\mathrm{M}=\mathrm{Ni}$
(c) $\mathrm{M}=\mathrm{Zn}$
(b) $\mathrm{M}=\mathrm{Cu}$
(d) $\mathbf{M}=\mathrm{Ba}$

David Collins

Numerade Educator

Problem 95

An unknown metal reacts with oxygen to give the metal oxide, MO $_{2} .$ Identify the metal if a $0.356-\mathrm{g}$ sample of the metal produces $0.452 \mathrm{g}$ of the metal oxide.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 96

Titanium(IV) oxide, $\mathrm{TiO}_{2},$ is heated in hydrogen gas to give water and a new titanium oxide, $\mathrm{Ti}_{x} \mathrm{O}_{y} .$ If $1.598 \mathrm{g}$ of $\mathrm{TiO}_{2}$ produces $1.438 \mathrm{g}$ of $\mathrm{Ti}_{x} \mathrm{O}_{y},$ what is the
empirical formula of the new oxide?

Ronald Prasad

Numerade Educator

Problem 97

Potassium perchlorate is prepared by the following sequence of reactions:
$\mathrm{Cl}_{2}(\mathrm{g})+2 \mathrm{KOH}(\mathrm{aq}) \rightarrow \mathrm{KCl}(\mathrm{aq})+\mathrm{KClO}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
$3 \mathrm{KClO}(\mathrm{aq}) \rightarrow 2 \mathrm{KCl}(\mathrm{aq})+\mathrm{KClO}_{3}(\mathrm{aq})$
$4 \mathrm{KClO}_{3}(\mathrm{aq}) \rightarrow 3 \mathrm{KClO}_{4}(\mathrm{aq})+\mathrm{KCl}(\mathrm{aq})$
What mass of $\mathrm{Cl}_{2}(\mathrm{g})$ is required to produce $234 \mathrm{kg}$ of $\mathrm{KClO}_{4} ?$

David Collins

Numerade Educator

Problem 98

Commercial sodium "hydrosulfite" is $90.1 \%$ $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4} .$ The sequence of reactions used to prepare the compound is
$$
\begin{array}{c}
\mathrm{Zn}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{g}) \rightarrow \mathrm{ZnS}_{2} \mathrm{O}_{4}(\mathrm{s}) \\
\mathrm{ZnS}_{2} \mathrm{O}_{4}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq}) \rightarrow \mathrm{ZnCO}_{3}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}(\mathrm{aq})
\end{array}
$$
(a) What mass of pure $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}$ can be prepared from $125 \mathrm{kg}$ of $\mathrm{Zn}, 500 . \mathrm{g}$ of $\mathrm{SO}_{2},$ and an excess of $\mathrm{Na}_{2} \mathrm{CO}_{3} ?$
(b) What mass of the commercial product would contain the $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}$ produced using the amounts of reactants in part (a)?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 99

What mass of lime, CaO, can be obtained by heating $125 \mathrm{kg}$ of limestone that is $95.0 \%$ by mass $\mathrm{CaCO}_{3} ?$
$$
\mathrm{CaCO}_{3}(\mathrm{s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})
$$

David Collins

Numerade Educator

Problem 100

The elements silver, molybdenum, and sulfur combine to form $\mathrm{Ag}_{2} \mathrm{MoS}_{4} .$ What is the maximum mass of $\mathrm{Ag}_{2} \mathrm{MoS}_{4}$ that can be obtained if $8.63 \mathrm{g}$ of silver, $3.36 \mathrm{g}$ of molybdenum, and $4.81 \mathrm{g}$ of sulfur are combined? (Hint: What is the limiting reactant?)

Ronald Prasad

Numerade Educator

Problem 101

A mixture of butene, $\mathrm{C}_{4} \mathrm{H}_{8},$ and butane, $\mathrm{C}_{4} \mathrm{H}_{10},$ is burned in air to give $\mathrm{CO}_{2}$ and water. Suppose you burn $2.86 \mathrm{g}$ of the mixture and obtain $8.80 \mathrm{g}$ of $\mathrm{CO}_{2}$ and $4.14 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} .$ What are the mass percentages of butene and butane in the mixture?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 102

Cloth can be waterproofed by coating it with a silicone layer. This is done by exposing the cloth to $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}$ vapor. The silicon compound reacts with OH groups on the cloth to form a waterproofing film (density $=1.0 \mathrm{g} / \mathrm{cm}^{3}$ ) of $\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n},$ where $n$ is a
large integer number.
$n\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}+2 n \mathrm{OH}^{-} \rightarrow$
$$
2 n \mathrm{Cl}^{-}+n \mathrm{H}_{2} \mathrm{O}+\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n}
$$
The coating is added layer by layer, with each layer of $\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n}$ being $0.60 \mathrm{nm}$ thick. Suppose you want to waterproof a piece of cloth that is 3.00 square meters, and you want 250 layers of waterproofing compound on the cloth. What mass of $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}$ do you need?

Ronald Prasad

Numerade Educator

Problem 103

Copper metal can be prepared by roasting copper ore, which can contain cuprite $\left(\mathrm{Cu}_{2} \mathrm{S}\right)$ and $\operatorname{copper}(\mathrm{II})$ sulfide.
$$
\begin{aligned}
\mathrm{Cu}_{2} \mathrm{S}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) & \rightarrow 2 \mathrm{Cu}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g}) \\
\mathrm{CuS}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) & \rightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g})
\end{aligned}
$$
Suppose an ore sample contains $11.0 \%$ impurity in addition to a mixture of CuS and Cu_S. Heating $100.0 \mathrm{g}$ of the mixture produces $75.4 \mathrm{g}$ of copper metal with a purity of $89.5 \% .$ What is the weight percent of CuS in the ore? The weight percent of $\mathrm{Cu}_{2} \mathrm{S}$ ?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 104

An Alka-Seltzer tablet contains exactly $100 .$ mg of citric $\operatorname{acid}, \mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7},$ plus some sodium bicarbonate. What
mass of sodium bicarbonate is required to consume
100. mg of citric acid by the following reaction?
$\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{NaHCO}_{3}(\mathrm{aq}) \rightarrow$
$$
3 \mathrm{H}_{2} \mathrm{O}(\ell)+3 \mathrm{CO}_{2}(\mathrm{g})+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})
$$

Ronald Prasad

Numerade Educator

Problem 105

Sodium bicarbonate and acetic acid react according to the equation
$\mathrm{NaHCO}_{3}(\mathrm{aq})+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(\mathrm{aq}) \rightarrow$
$$
\mathrm{NaCH}_{3} \mathrm{CO}_{2}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$
What mass of sodium acetate can be obtained from mixing $15.0 \mathrm{g}$ of $\mathrm{NaHCO}_{3}$ with $125 \mathrm{mL}$ of $0.15 \mathrm{M}$ acetic acid?

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 106

A noncarbonated soft drink contains an unknown amount of citric acid, $\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7} .$ If $100 .$ mL of the soft drink requires $33.51 \mathrm{mL}$ of $0.0102 \mathrm{M} \mathrm{NaOH}$ to neutralize the citric acid completely, what mass of citric acid does the soft drink contain per $100 .$ mL? The reaction of citric acid and NaOH is
$\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{NaOH}(\mathrm{aq}) \rightarrow$
$$
\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{H}_{2} \mathrm{O}(\ell)
$$

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 107

Sodium thiosulfate, $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3},$ is used as a "fixer" in black-and-white photography. Suppose you have a bottle of sodium thiosulfate and want to determine its purity. The thiosulfate ion can be oxidized with $\mathrm{I}_{2}$ according to the balanced, net ionic equation
$$
\mathrm{I}_{2}(\mathrm{aq})+2 \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(\mathrm{aq}) \rightarrow 2 \mathrm{I}^{-}(\mathrm{aq})+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}(\mathrm{aq})
$$
If you use $40.21 \mathrm{mL}$ of $0.246 \mathrm{M} \mathrm{I}_{2}$ in a titration, what is the weight percent of $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ in a 3.232 -g sample of impure material?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 108

You have a mixture of oxalic acid, $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},$ and another solid that does not react with sodium hydroxide. If $29.58 \mathrm{mL}$ of $0.550 \mathrm{M} \mathrm{NaOH}$ is required to titrate the oxalic acid in the 4.554 -g sample to the second equivalence point, what is the mass percent of oxalic acid in the mixture? Oxalic acid and $\mathrm{NaOH}$ react according to the equation
$\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow$
$\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$

Ronald Prasad

Numerade Educator

Problem 109

(a) What is the pH of a 0.105 M HCl solution?
(b) What is the hydronium ion concentration in a solution with a pH of $2.56 ?$ Is the solution acidic or basic?
(c) A solution has a pH of $9.67 .$ What is the hydronium ion concentration in the solution? Is the solution acidic or basic?
(d) A 10.0 -mL sample of 2.56 $\mathrm{M}$ HCl is diluted with water to $250 .$ mL. What is the pH of the dilute solution?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 110

A solution of hydrochloric acid has a volume of $125 \mathrm{mL}$ and a pH of $2.56 .$ What mass of $\mathrm{NaHCO}_{3}$ must be added to completely consume the HCl?

Ronald Prasad

Numerade Educator

Problem 111

One half liter $(500 . \mathrm{mL})$ of $2.50 \mathrm{M} \mathrm{HCl}$ is mixed with $250 .$ mL of $3.75 \mathrm{M} \mathrm{HCl}$. Assuming the total solution volume after mixing is $750 . \mathrm{mL},$ what is the concentration of hydrochloric acid in the resulting solution? What is its pH?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 112

A solution of hydrochloric acid has a volume of $250 . \mathrm{mL}$ and a pH of $1.92 .$ Exactly $250 .$ mL of $0.0105 \mathrm{M} \mathrm{NaOH}$ is added. What is the $\mathrm{pH}$ of the resulting solution?

Angelina Chavez

Angelina Chavez

Numerade Educator

Problem 113

You place $2.56 \mathrm{g}$ of $\mathrm{CaCO}_{3}$ in a beaker containing
250. mL of 0.125 M HCl. When the reaction has ceased, does any calcium carbonate remain? What mass of $\mathrm{CaCl}_{2}$ can be produced?
$\mathrm{CaCO}_{3}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow$
$$
\mathrm{CaCl}_{2}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 114

The cancer drug cisplatin, $\operatorname{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2},$ can be made by reacting (NH_/) $_{2} \mathrm{PtCl}_{4}$ with ammonia in aqueous solution. Besides cisplatin, the other product is $\mathrm{NH}_{4} \mathrm{Cl}$.
(a) Write a balanced equation for this reaction.
(b) To obtain $12.50 \mathrm{g}$ of cisplatin, what mass of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{PtCl}_{4}$ is required? What volume of $0.125 \mathrm{M}$
$\mathrm{NH}_{3}$ is required?
(c) A Cisplatin can react with the organic compound pyridine, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N},$ to form a new compound.
$$
\operatorname{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}(\mathrm{aq})+x \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}(\mathrm{aq}) \rightarrow
$$
Suppose you treat $0.150 \mathrm{g}$ of cisplatin with what you believe is an excess of liquid pyridine $(1.50 \mathrm{mL} ; d=$ $0.979 \mathrm{g} / \mathrm{mL}) .$ When the reaction is complete, you can find out how much pyridine was not used by titrating the solution with standardized HCl. If 37.0 mL of $0.475 \mathrm{M} \mathrm{HCl}$ is required to titrate the excess pyridine,
$$
\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})
$$
what is the formula of the unknown compound $\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\left(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}\right)_{x} ?$

Ronald Prasad

Numerade Educator

Problem 115

You need to know the volume of water in a small swimming pool, but, owing to the pool's irregular shape, it is not a simple matter to determine its dimensions and calculate the volume. To solve the problem, you stir in a solution of a dye ( $1.0 \mathrm{g}$ of methylene blue, $\mathrm{C}_{16} \mathrm{H}_{18} \mathrm{ClN}_{3} \mathrm{S}$,
in $50.0 \mathrm{mL}$ of water). After the dye has mixed with the water in the pool, you take a sample of the water. Using a spectrophotometer, you determine that the concentration of the dye in the pool is $4.1 \times 10^{-8} \mathrm{M} .$ What is the volume of water in the pool?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 116

Calcium and magnesium carbonates occur together in the mineral dolomite. Suppose you heat a sample of the mineral to obtain the oxides, $\mathrm{CaO}$ and $\mathrm{MgO}$, and then treat the oxide sample with hydrochloric acid. If $7.695 \mathrm{g}$ of the oxide sample requires $125 \mathrm{mL}$ of $2.55 \mathrm{M} \mathrm{HCl}$
$$
\begin{aligned}
\mathrm{CaO}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) & \rightarrow \mathrm{CaCl}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \\
\mathrm{MgO}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) & \rightarrow \mathrm{MgCl}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)
\end{aligned}
$$
what is the weight percent of each oxide (CaO and $\mathrm{MgO})$ in the sample?

Rashmi Sinha

Numerade Educator

Problem 117

Gold can be dissolved from gold-bearing rock by treating the rock with sodium cyanide in the presence of oxygen.
$4 \mathrm{Au}(\mathrm{s})+8 \mathrm{NaCN}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow$
$$
4 \mathrm{NaAu}(\mathrm{CN})_{2}(\mathrm{aq})+4 \mathrm{NaOH}(\mathrm{aq})
$$
(a) Name the oxidizing and reducing agents in this reaction. What has been oxidized, and what has been reduced?
(b) If you have exactly one metric ton $(1 \text { metric ton }=$ $1000 \mathrm{kg})$ of gold-bearing rock, what volume of $0.075 \mathrm{M} \mathrm{NaCN},$ in liters, do you need to extract the gold if the rock is $0.019 \%$ gold?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 118

You mix $25.0 \mathrm{mL}$ of $0.234 \mathrm{M} \mathrm{FeCl}_{3}$ with $42.5 \mathrm{mL}$
of $0.453 \mathrm{M} \mathrm{NaOH}$
(a) What mass of $\mathrm{Fe}(\mathrm{OH})_{3}$ (in grams) will precipitate from this reaction mixture?
(b) One of the reactants $\left(\mathrm{FeCl}_{3} \text { or } \mathrm{NaOH}\right)$ is present in a stoichiometric excess. What is the molar concentration of the excess reactant remaining in solution after $\mathrm{Fe}(\mathrm{OH})_{3}$. has been precipitated?

Ronald Prasad

Numerade Educator

Problem 119

One type of reaction used in the chemical industry is a substitution, where one atom or group is exchanged for another. In this reaction, an alcohol, 1-butanol, is transformed into 1-bromobutane by substituting Br for the -OH group in the presence of sulfuric acid.
$$
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{NaBr}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow
$$
Calculate the \% atom economy for the desired product, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 120

Ethylene oxide, $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O},$ is an important industrial chemical [as it is the starting place to make such important chemicals as ethylene glycol (antifreeze) and various polymers]. One way to make the compound is called the "chlorohydrin route."
$\mathrm{C}_{2} \mathrm{H}_{4}+\mathrm{Cl}_{2}+\mathrm{Ca}(\mathrm{OH})_{2} \rightarrow \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}+\mathrm{CaCl}_{2}+\mathrm{H}_{2} \mathrm{O}$
Another route is the modern catalytic reaction.
$$
\mathrm{C}_{2} \mathrm{H}_{4}+1 / 2 \mathrm{O}_{2} \rightarrow \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}
$$
(a) Calculate the \% atom economy for the production of $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$ in each of these reactions. Which is the more efficient method?
(b) What is the percent yield of $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$ if 867 g of $\mathrm{C}_{2} \mathrm{H}_{4}$ is used to synthesize $762 \mathrm{g}$ of the product by the catalytic reaction?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 121

Suppose you dilute $25.0 \mathrm{mL}$ of a $0.110 \mathrm{M}$ solution of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ to exactly $100.0 \mathrm{mL}$. You then take exactly $10.0 \mathrm{mL}$ of this diluted solution and add it to a $250-\mathrm{mL}$ volumetric flask. After filling the volumetric flask to the mark with distilled water (indicating the volume of the new solution is $250 . \mathrm{mL}$ ), what is the concentration of the diluted $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 122

In some laboratory analyses, the preferred technique is to dissolve a sample in an excess of acid or base and then "back-titrate" the excess with a standard base or acid. This technique is used to assess the purity of a sample of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} .$ Suppose you dissolve a $0.475-\mathrm{g}$ sample of impure $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ in aqueous KOH. $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}(\mathrm{aq})+2 \mathrm{KOH}(\mathrm{aq}) \rightarrow$
$$
2 \mathrm{NH}_{3}(\mathrm{aq})+\mathrm{K}_{2} \mathrm{SO}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)
$$
The $\mathrm{NH}_{3}$ liberated in the reaction is distilled from the solution into a flask containing $50.0 \mathrm{mL}$ of $0.100 \mathrm{M}$ HCl. The ammonia reacts with the acid to produce $\mathrm{NH}_{4} \mathrm{Cl},$ but not all of the HCl is used in this reaction. The amount of excess acid is determined by titrating the solution with standardized NaOH. This titration consumes $11.1 \mathrm{mL}$ of $0.121 \mathrm{M} \mathrm{NaOH} .$ What is the weight percent of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ in the 0.475 -g sample?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 123

Oyster beds in the oceans require chloride ions for growth. The minimum concentration is $8 \mathrm{mg} / \mathrm{L}$ (8 parts per million). To analyze for the amount of chloride ion in a 50.0 -mL sample of water, you add a few drops of aqueous potassium chromate and then titrate the sample with $25.60 \mathrm{mL}$ of $0.001036 \mathrm{M}$ silver nitrate. The silver nitrate reacts with chloride ion, and, when the ion is completely removed, the silver nitrate reacts with potassium chromate to give a red precipitate.
(a) Write a balanced net ionic equation for the reaction of silver nitrate with chloride ions.
(b) Write a complete balanced equation and a net ionic equation for the reaction of silver nitrate with potassium chromate, indicating whether each compound is water-soluble or not.
(c) What is the concentration of chloride ions in the sample? Is it sufficient to promote oyster growth?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 124

A compound consisting of yttrium(III) ions, barium(II) ions, both copper(II) and copper(III) ions, and oxide ions is a superconducting material at low temperatures (page 135 ). It has the formula $\mathrm{YBa}_{2} \mathrm{Cu}_{3} \mathrm{O}_{7-x}$ where $x$ is a variable between 1 and $0 .$ To find out the value of $x,$ you dissolve $34.02 \mathrm{mg}$ of the compound in $5 \mathrm{mL}$ of $1.0 \mathrm{M}$ HCl. Bubbles of oxygen gas $\left(\mathrm{O}_{2}\right)$ are observed as the following reaction occurs:
$\mathrm{YBa}_{2} \mathrm{Cu}_{3} \mathrm{O}_{7-\mathrm{x}}(\mathrm{s})+13 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow$
$$
\begin{aligned}
\mathrm{Y}^{3+}(\mathrm{aq})+2 \mathrm{Ba}^{2+}(\mathrm{aq})+3 \mathrm{Cu}^{2+}(\mathrm{aq}) & \\
+1 / 4(1-2 x) \mathrm{O}_{2}(\mathrm{g})+13 / 2 \mathrm{H}_{2} \mathrm{O}(\ell)
\end{aligned}
$$
You then boil the solution, cool it, and add $10 \mathrm{mL}$ of $0.70 \mathrm{M} \mathrm{KI}$ under argon. The following reaction occurs:
$$
2 \mathrm{Cu}^{2+}(\mathrm{aq})+5 \mathrm{I}^{-}(\mathrm{aq}) \rightarrow 2 \mathrm{CuI}(\mathrm{s})+\mathrm{I}_{3}^{-}(\mathrm{aq})
$$
When this reaction is complete, a titration of the resulting solution with sodium thiosulfate requires $1.542 \times 10^{-4} \mathrm{mol} \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(\mathrm{aq})$
$$
\mathrm{I}_{3}^{-}(\mathrm{aq})+2 \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(\mathrm{aq}) \rightarrow 3 \mathrm{I}^{-}(\mathrm{aq})+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}(\mathrm{aq})
$$
What is the value of $x$ in $\mathrm{YBa}_{2} \mathrm{Cu}_{3} \mathrm{O}_{7-x} ?$

Victor Salazar

Numerade Educator

Problem 125

You wish to determine the weight percent of copper in a copper-containing alloy. After dissolving a $0.251-\mathrm{g}$ sample of the alloy in acid, an excess of KI is added, and the $\mathrm{Cu}^{2+}$ and $\mathrm{I}^{-}$ ions undergo the reaction
$$
2 \mathrm{Cu}^{2+}(\mathrm{aq})+5 \mathrm{I}^{-}(\mathrm{aq}) \rightarrow 2 \mathrm{CuI}(\mathrm{s})+\mathrm{I}_{3}^{-}(\mathrm{aq})
$$
The liberated $\mathrm{I}_{3}^{-}$ is titrated with sodium thiosulfate according to the equation
$$
\mathrm{I}_{3}^{-}(\mathrm{aq})+2 \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(\mathrm{aq}) \rightarrow \mathrm{S}_{4} \mathrm{O}_{6}^{2-}(\mathrm{aq})+3 \mathrm{I}^{-}(\mathrm{aq})
$$
(a) Designate the oxidizing and reducing agents in the two reactions above.
(b) If $26.32 \mathrm{mL}$ of $0.101 \mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ is required for
titration to the equivalence point, what is the weight percent of Cu in the alloy?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 126

A compound has been isolated that can have either of two possible formulas: $(a) K\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]$ or
(b) $\mathrm{K}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right] .$ To find which is correct, you dissolve
a weighed sample of the compound in acid, forming oxalic acid, $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$. You then titrate this acid with potassium permanganate, $\mathrm{KMnO}_{4}$ (the source of the $\left.\mathrm{MnO}_{4}^{-} \text {ion }\right) .$ The balanced, net ionic equation for the titration is
$$
\begin{aligned}
5 \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{MnO}_{4}^{-}(\mathrm{aq})+6 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) & \rightarrow \\
2 \mathrm{Mn}^{2+}(\mathrm{aq})+10 \mathrm{CO}_{2}(\mathrm{g})+14 \mathrm{H}_{2} \mathrm{O}(\ell)
\end{aligned}
$$
Titration of $1.356 \mathrm{g}$ of the compound requires $34.50 \mathrm{mL}$ of $0.108 \mathrm{M} \mathrm{KMnO}_{4} .$ Which is the correct formula of the iron-containing compound: (a) or (b)?

Ronald Prasad

Numerade Educator

Problem 127

A Chromium(III) chloride forms many compounds with ammonia. To find the formula of one of these compounds, you titrate the $\mathrm{NH}_{3}$ in the compound with standardized acid.
$\operatorname{Cr}\left(\mathrm{NH}_{3}\right)_{x} \mathrm{Cl}_{3}(\mathrm{aq})+x \mathrm{HCl}(\mathrm{aq}) \rightarrow$
$$
x \mathrm{NH}_{4}^{+}(\mathrm{aq})+\mathrm{Cr}^{3+}(\mathrm{aq})+(x+3) \mathrm{Cl}^{-}(\mathrm{aq})
$$
Assume that $24.26 \mathrm{mL}$ of $1.500 \mathrm{M} \mathrm{HCl}$ is used to titrate $1.580 \mathrm{g}$ of $\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{x} \mathrm{Cl}_{3} .$ What is the value of $x ?$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 128

Thioridazine, $\mathrm{C}_{21} \mathrm{H}_{26} \mathrm{N}_{2} \mathrm{S}_{2},$ is a pharmaceutical agent used to regulate dopamine. (Dopamine, a neurotransmitter, affects brain processes that control movement, emotional response, and ability to experience pleasure and pain.) A chemist can analyze a sample of the pharmaceutical for the thioridazine content by decomposing it to convert the sulfur in the compound to sulfate ion. This is then "trapped" as water-insoluble barium sulfate (see Figure $4.4)$
$\mathrm{SO}_{4}^{2-}(\mathrm{aq}, \text { from thioridazine })+\mathrm{BaCl}_{2}(\mathrm{aq}) \rightarrow$
$\mathrm{BaSO}_{4}(\mathrm{s})+2 \mathrm{Cl}^{-}(\mathrm{aq})$
Suppose a 12 -tablet sample of the drug yielded $0.301 \mathrm{g}$ of BaSO_.. What is the thioridazine content, in milligrams, of each tablet?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 129

A herbicide contains $2,4-\mathrm{D}(2,4-$ dichlorophenoxyacetic acid), $\mathrm{C}_{8} \mathrm{H}_{6} \mathrm{Cl}_{2} \mathrm{O}_{3}$. A 1.236 -g sample of the herbicide was decomposed to liberate the chlorine as $\mathrm{Cl}^{-}$ ion. This was precipitated as $\mathrm{AgCl}$, with a mass of $0.1840 \mathrm{g}$. What is the mass percent of $2,4-\mathrm{D}$ in the sample?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 130

Sulfuric acid is listed in a catalog with a concentration of $95-98 \% .$ A bottle of the acid in the stockroom states that 1.00 L has a mass of $1.84 \mathrm{kg}$. To determine the concentration of sulfuric acid in the stockroom bottle, a student dilutes $5.00 \mathrm{mL}$ to $500 .$ mL. She then takes four 10.00 -mL samples and titrates each with standardized sodium hydroxide $(c=0.1760 \mathrm{M})$
\begin{tabular}{lcccc}
Sample & 1 & 2 & 3 & 4 \\
Volume $\mathrm{NaOH}(\mathrm{mL})$ & 20.15 & 21.30 & 20.40 & 20.35 \\
\hline
\end{tabular}
(a) What is the average concentration of the diluted sulfuric acid sample?
(b) What is the mass percent of $\mathrm{H}_{2} \mathrm{SO}_{4}$ in the original bottle of the acid?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 131

Anhydrous calcium chloride is a good drying agent because it will rapidly pick up water. Suppose you have stored some carefully dried $\mathrm{CaCl}_{2}$ in a desiccator. Unfortunately, someone did not close the top of the desiccator tightly, and the $\mathrm{CaCl}_{2}$ became partially hydrated. A $150-\mathrm{g}$ sample of this partially hydrated material was dissolved in $80 \mathrm{g}$ of hot water. When the solution was cooled to $20^{\circ} \mathrm{C}, 74.9 \mathrm{g}$ of $\mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$
precipitated. Knowing the solubility of calcium chloride in water at $20^{\circ} \mathrm{C}$ is $74.5 \mathrm{g} \mathrm{CaCl}_{2} / 100 \mathrm{g}$ water, determine the water content of the $150-\mathrm{g}$ sample of partially hydrated calcium chloride (in moles of water per mole of $\left.\mathrm{CaCl}_{2}\right)$.

Victor Salazar

Numerade Educator

Problem 132

$0.5510-\mathrm{g}$ sample consisting of a mixture of iron and iron(III) oxide was dissolved completely in acid to give a solution containing iron(II) and iron(III) ions. A reducing agent was added to convert all of the iron to iron(II) ions, and the solution was then titrated with the standardized $\mathrm{KMnO}_{4}(0.04240 \mathrm{M}) ; 37.50 \mathrm{mL}$ of the
$\mathrm{KMnO}_{4}$ solution was required. Calculate the mass percent of $\mathrm{Fe}$ and $\mathrm{Fe}_{2} \mathrm{O}_{3}$ in the 0.5510 -g sample. (Example 4.13 gives the equation for the reaction of iron(II) ions and $\mathrm{KMnO}_{4}$.)

Ronald Prasad

Numerade Educator

Problem 133

Phosphate in urine can be determined by spectrophotometry. After removing protein from the sample, it is treated with a molybdenum compound to give, ultimately, a deep blue polymolybdate. The absorbance of the blue polymolybdate can be measured at $650 \mathrm{nm}$ and is directly related to the urine phosphate concentration. A 24 -hour urine sample was collected from a patient; the volume of urine was $1122 \mathrm{mL}$. The phosphate in a $1.00 \mathrm{mL}$ portion of the urine sample was converted to the blue polymolybdate and diluted to $50.00 \mathrm{mL} .$ A calibration curve was prepared using phosphate-containing solutions. (Concentrations are reported in grams of phosphorus (P) per liter of solution.)
(a) What are the slope and intercept of the calibration curve?
(b) What is the mass of phosphorus per liter of urine?
(c) What mass of phosphate did the patient excrete in the one-day period?

Ronald Prasad

Numerade Educator

Problem 134

A 4.000 -g sample containing $\mathrm{KCl}$ and $\mathrm{KClO}_{4}$ was dissolved in sufficient water to give $250.00 \mathrm{mL}$ of solution. A 50.00 -mL portion of the solution required $41.00 \mathrm{mL}$ of $0.0750 \mathrm{M} \mathrm{AgNO}_{3}$ in a Mohr titration
(page 172 ). Next, a 25.00 -mL portion of the original solution was treated with $\mathrm{V}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ to reduce the perchlorate ion to chloride,
$8 \mathrm{V}^{3+}(\mathrm{aq})+\mathrm{ClO}_{4}^{-}(\mathrm{aq})+12 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow$
$\mathrm{Cl}^{-}(\mathrm{aq})+8 \mathrm{VO}^{2+}(\mathrm{aq})+8 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq})$
and the resulting solution was titrated with $\mathrm{AgNO}_{3}$. This titration required $38.12 \mathrm{mL}$ of $0.0750 \mathrm{M} \mathrm{AgNO}_{3}$ What is the mass percent of KCl and $\mathrm{KClO}_{4}$ in the mixture?

Victor Salazar

Numerade Educator

Problem 135

Two beakers sit on a balance; the total mass is $167.170 \mathrm{g} .$ One beaker contains a solution of $\mathrm{KI} ;$ the other contains a solution of $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} .$ When the solution in one beaker is poured completely into the other, the following reaction occurs:
$$
2 \mathrm{KI}(\mathrm{aq})+\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq}) \rightarrow 2 \mathrm{KNO}_{3}(\mathrm{aq})+\mathrm{PbI}_{2}(\mathrm{s})
$$
What is the total mass of the beakers and solutions after reaction? Explain completely.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 136

A weighed sample of iron (Fe) is added to liquid bromine $\left(\mathrm{Br}_{2}\right)$ and allowed to react completely. The reaction produces a single product, which can be isolated and weighed. The experiment was repeated a number of times with different masses of iron but with the same mass of bromine (see graph below).
(a) What mass of $\mathrm{Br}_{2}$ is used when the reaction consumes $2.0 \mathrm{g}$ of $\mathrm{Fe}$ ?
(b) What is the mole ratio of $\mathrm{Br}_{2}$ to Fe in the reaction?
(c) What is the empirical formula of the product?
(d) Write the balanced chemical equation for the reaction of iron and bromine.
(e) What is the name of the reaction product?
(f) Which statcment or statcments bcst describc the experiments summarized by the graph?
(i) When $1.00 \mathrm{g}$ of $\mathrm{Fe}$ is added to the $\mathrm{Br}_{2}, \mathrm{Fe}$ is the limiting reagent.
(ii) When $3.50 \mathrm{g}$ of $\mathrm{Fe}$ is added to the $\mathrm{Br}_{2},$ there is an excess of $\mathrm{Br}_{2}$
(iii) When $2.50 \mathrm{g}$ of $\mathrm{Fe}$ is added to the $\mathrm{Br}_{2},$ both reactants are used up completely.
(iv) When $2.00 \mathrm{g}$ of $\mathrm{Fe}$ is added to the $\mathrm{Br}_{2}, 10.8 \mathrm{g}$ of product is formed. The percent yield must therefore be $20.0 \%$

Ronald Prasad

Numerade Educator

Problem 137

Let us explore a reaction with a limiting reactant. Here, zinc metal is added to a flask containing aqueous HCl, and $\mathrm{H}_{2}$ gas is a product.
$$
\mathrm{Zn}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{ZnCl}_{2}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{g})
$$
The three flasks each contain 0.100 mol of HCl. Zinc is added to each flask in the following quantities.
When the reactants are combined, the $\mathrm{H}_{2}$ inflates the balloon attached to the flask. The results are as follows:
Flask 1: Balloon inflates completely, but some $\mathrm{Zn}$ remains when inflation ceases. Flask 2: Balloon inflates completely. No Zn remains. Flask 3: Balloon does not inflate completely. No Zn remains.
Explain these results. Perform calculations that support your explanation.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 138

The reaction of aluminum and bromine is pictured below. The white solid on the lip of the beaker at the end of the reaction is $\mathrm{Al}_{2} \mathrm{Br}_{6} .$ In the reaction pictured below, which was the limiting reactant, Al or $\mathrm{Br}_{2} ?$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 139

Two students titrate different samples of the same solution of HCl using 0.100 M NaOH solution and phenolphthalein indicator (Figure 4.12 ). The first student pipets $20.0 \mathrm{mL}$ of the HCl solution into a flask, adds $20 \mathrm{mI}$. of distilled water and a few drops of phenolphthalein solution, and titrates until a lasting pink color appears. The second student pipets $20.0 \mathrm{mL}$ of the HCl solution into a flask, adds $60 \mathrm{mL}$ of distilled water and a few drops of phenolphthalein solution, and titrates to the first lasting pink color. Each student correctly calculates the molarity of an HCl solution. What will the second student's result be?
(a) four times less than the first student's result
(b) four times greater than the first student's result
(c) two times less than the first student's result
(d) two times greater than the first student's result
(e) the same as the first student's result

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 140

In most states, a person will receive a "driving while intoxicated" (DWI) ticket if the blood alcohol level (BAL) is 80 mg per deciliter (dL) of blood or higher. Suppose a person is found to have a BAL of 0.033 mol of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ per liter of blood. Will the person receive a DWI ticket?

Ronald Prasad

Numerade Educator

Problem 141

Benzene, $\mathrm{C}_{6} \mathrm{H}_{6},$ is a common compound, and it can be oxidized to give maleic anhydride, $\mathrm{C}_{4} \mathrm{H}_{2} \mathrm{O}_{3},$ which is used in turn to make other important compounds.
(a) What is the \% atom economy for the synthesis of maleic anhydride from benzene by this reaction?
(b) If 972 g of maleic anhydride is produced from exactly $1.00 \mathrm{kg}$ of benzene, what is the percent yield of the anhydride? What mass of the byproduct $\mathrm{CO}_{2}$
is also produced?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 142

Maleic anhydride, $\mathrm{C}_{4} \mathrm{H}_{2} \mathrm{O}_{3},$ can be produced by the oxidation of benzene (Study Question 141 ). It can also be produced from the oxidation of butene.
(a) What is the \% atom economy for the synthesis of maleic anhydride from butene by this reaction?
(b) If $1.02 \mathrm{kg}$ of maleic anhydride is produced from exactly $1.00 \mathrm{kg}$ of butene, what is the percent yield of the anhydride? What mass of the byproduct $\mathrm{H}_{2} \mathrm{O}$ is also produced?

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator