Chemistry: Atoms First

Julia Burdge; Jason Overby

Chapter 9

CHEMICAL REACTIONS IN AQUEOUS SOLUTIONS - all with Video Answers

Educators

Chapter Questions

Problem 1

Define solute, solvent, and solution by describing the process of dissolving a solid in a liquid.

SK

Sara Kolms

Numerade Educator

Problem 2

What is the difference between a nonelectrolyte and an electrolyte? Between a weak electrolyte and a strong electrolyte?

Breanna Kloczkowski

Breanna Kloczkowski

Numerade Educator

Problem 3

What is the difference between the symbols ⟶ and ⟹ in chemical equations?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 4

Although water is classified as a nonelectrolyte, in reality it is an extremely weak electrolyte and therefore cannot conduct electricity. Nevertheless, it can be dangerous to operate electrical appliances with wet hands. Explain.

SK

Sara Kolms

Numerade Educator

Problem 5

Identify the species present in aqueous solutions of the following strong electrolytes: (a) LiF , (b) $\mathrm{NH}_4 \mathrm{NO}_3$, (c) $\mathrm{CaBr}_2$, (d) $\mathrm{Na}_2 \mathrm{CO}_3$.

Natalie Johns

Numerade Educator

Problem 6

The passage of electricity through an electrolyte solution is caused by the movement of (a) electrons only, (b) cations only, (c) anions only, (d) both cations and anions.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 7

You are given a water-soluble compound X . Describe how you would determine whether it is an electrolyte or a nonelectrolyte. If it is an electrolyte, how would you determine whether it is strong or weak?

Himanshu Garg

Numerade Educator

Problem 8

These diagrams show aqueous solutions of three different compounds: (a) AB , (b) AC , and (c) AD . Arrange the compounds in order of increasing electrolyte strength.

SK

Sara Kolms

Numerade Educator

Problem 9

These diagrams show aqueous solutions of three different compounds: (a) $\mathrm{A}_2 \mathrm{E}$, (b) $\mathrm{A}_2 \mathrm{~F}$, and (c) $\mathrm{A}_2 \mathrm{G}$. Arrange the compounds in order of increasing electrolyte strength.

AA

A Adly

Numerade Educator

Problem 10

The aqueous solutions of three compounds are shown in the diagram. Identify each compound as a nonelectrolyte, a weak electrolyte, or a strong electrolyte.

Brittany Collins

Brittany Collins

Numerade Educator

Problem 11

Which of the following diagrams best represents the hydration of NaCl when dissolved in water? The $\mathrm{Cl}^{-}$ ion is larger in size than the $\mathrm{Na}^{+}$ion.

NB

Nimrat Brar

Numerade Educator

Problem 12

Identify each of the following substances as a strong electrolyte, weak electrolyte, or nonelectrolyte:
(a) $\mathrm{H}_2 \mathrm{O}$, (b) KCl , (c) $\mathrm{HNO}_3$, (d) $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$, (e) $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$.

Brittany Collins

Brittany Collins

Numerade Educator

Problem 13

Identify each of the following substances as a strong electrolyte, weak electrolyte, or nonelectrolyte:
(a) $\mathrm{Ba}\left(\mathrm{NO}_3\right)_2$, (b) Ne , (c) $\mathrm{NH}_3$, (d) NaOH , (e) HF .

Brittany Collins

Brittany Collins

Numerade Educator

Problem 14

Describe hydration. What properties of water enable its molecules to interact with ions in solution?

SK

Sara Kolms

Numerade Educator

Problem 15

What is the difference between a molecular equation and an ionic equation? Between an ionic equation and a net ionic equation? What is the advantage of writing net ionic equations?

SK

Sara Kolms

Numerade Educator

Problem 16

Two aqueous solutions of KOH and $\mathrm{MgCl}_2$ are mixed. Which of the following diagrams best represents the resulting combination?

Brittany Collins

Brittany Collins

Numerade Educator

Problem 17

Two aqueous solutions of $\mathrm{AgNO}_3$ and NaCl are mixed. Which of the following diagrams best represents the mixture?
$$
\mathrm{Ag}^{+}-\mathrm{Cl}-\mathrm{O} \quad \mathrm{Na}^{+}-\mathrm{O} \quad \mathrm{NO}_3^{-}-\mathrm{O}
$$

Brittany Collins

Brittany Collins

Numerade Educator

Problem 18

Which reaction is represented by the net ionic equation for the combination of aqueous solutions of $\mathrm{LiNO}_3$ and $\mathrm{NaC}_2 \mathrm{H}_3 \mathrm{O}_2$ ?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 19

Which reaction is represented by the net ionic equation for the combination of aqueous solutions of LiOH and $\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$ ?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 20

Characterize the following compounds as soluble or insoluble in water: (a) $\mathrm{CaCO}_3$, (b) $\mathrm{ZnSO}_4$, (c) $\mathrm{Hg}\left(\mathrm{NO}_3\right)_2$, (d) $\mathrm{HgSO}_4$, (e) $\mathrm{NH}_4 \mathrm{ClO}_4$ -

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 21

Characterize the following compounds as soluble or insoluble in water: (a) $\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$, (b) $\mathrm{Mn}(\mathrm{OH})_2$, (c) $\mathrm{AgClO}_3$, (d) $\mathrm{K}_2 \mathrm{~S}$, (e) $\mathrm{Pb}_3\left(\mathrm{PO}_4\right)_2$.

Nicole Smina

Numerade Educator

Problem 22

Write ionic and net ionic equations for the following reactions:
(a) $\mathrm{Na}_2 \mathrm{~S}(a q)+\mathrm{ZnCl}_2(a q) \longrightarrow$
(b) $\mathrm{K}_3 \mathrm{PO}_4(a q)+3 \mathrm{Sr}\left(\mathrm{NO}_3\right)_2(a q) \longrightarrow$
(c) $\mathrm{Mg}\left(\mathrm{NO}_3\right)_2(a q)+2 \mathrm{NaOH}(a q) \longrightarrow$

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 23

Write ionic and net ionic equations for the following reactions:
(a) $\mathrm{AgNO}_3(a q)+\mathrm{Na}_2 \mathrm{SO}_4(a q) \longrightarrow$
(b) $\mathrm{BaCl}_2(a q)+\mathrm{ZnSO}_4(a q) \longrightarrow$
(c) $\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3(a q)+\mathrm{CaCl}_2(a q) \longrightarrow$

SK

Sara Kolms

Numerade Educator

Problem 24

Which of the following processes will likely result in a precipitation reaction? (a) Mixing a $\mathrm{FeCl}_3$ solution with a LiOH solution; (b) mixing a $\mathrm{KNO}_3$ solution with a $\mathrm{CaCl}_2$ solution; (c) mixing a $\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3$ solution with a $\mathrm{Na}_2 \mathrm{CO}_3$ solution; (d) mixing a $\mathrm{Sr}\left(\mathrm{NO}_3\right)_2$ solution with a $\mathrm{Ca}(\mathrm{OH})_2$ solution. For mixtures that result in precipitation, write the formula of the precipitate.

Iva Lazarova

Numerade Educator

Problem 25

Which of the following processes will likely result in a precipitation reaction? (a) Mixing a $\mathrm{NaNO}_3$ solution with a $\mathrm{CuSO}_4$ solution; (b) mixing a $\mathrm{BaCl}_2$ solution with a $\mathrm{K}_2 \mathrm{SO}_4$ solution; (c) mixing a $\mathrm{AgNO}_3$ solution with a $\mathrm{LiC}_2 \mathrm{H}_3 \mathrm{O}_2$ solution. Write a net ionic equation for each combination.

Himanshu Garg

Numerade Educator

Problem 26

List the general properties of acids and bases.

SK

Sara Kolms

Numerade Educator

Problem 27

Give Arrhenius's and Bronsted's definitions of an acid and a base. Why are Bronsted's definitions more useful in describing acid-base properties?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 28

Give an example of a monoprotic acid, a diprotic acid, and a triprotic acid.

SK

Sara Kolms

Numerade Educator

Problem 29

What are the products of an acid-base neutralization reaction?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 30

What factors qualify a compound as a salt? Specify which of the following compounds are salts: $\mathrm{CH}_4, \mathrm{NaF}$, $\mathrm{NaOH}, \mathrm{CaO}, \mathrm{BaSO}_4, \mathrm{HNO}_3, \mathrm{NH}_3, \mathrm{KBr}$.

SK

Sara Kolms

Numerade Educator

Problem 31

Identify the following as a weak or strong acid or base: (a) $\mathrm{NH}_3$, (b) $\mathrm{H}_3 \mathrm{PO}_4$, (c) LiOH , (d) HCOOH (formic acid), (e) $\mathrm{H}_2 \mathrm{SO}_4$, (f) HF , (g) $\mathrm{Ba}(\mathrm{OH})_2$.
oblems

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 32

Identify each of the following species as a Bronsted acid, base, or both: (a) HI , (b) $\mathrm{C}_2 \mathrm{H}_3 \mathrm{O}_2^{-}$(c) $\mathrm{H}_2 \mathrm{PO}_4^{-}$, (d) $\mathrm{HSO}_4^{-}$.

Himanshu Garg

Numerade Educator

Problem 33

Identify each of the following species as a Bronsted acid, base, or both: (a) $\mathrm{PO}_4^{3-}$ (b) $\mathrm{ClO}_2^{-}$(c) $\mathrm{NH}_4^{+}$(d) $\mathrm{HCO}_3^{-}$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 34

Balance the following equations and write the corresponding ionic and net ionic equations (if appropriate):
(a) $\mathrm{HBr}(a q)+\mathrm{NH}_3(a q) \longrightarrow$
(b) $\mathrm{Ba}(\mathrm{OH})_2(a q)+\mathrm{H}_3 \mathrm{PO}_4(a q) \longrightarrow$
(c) $\mathrm{HClO}_4(a q)+\mathrm{Mg}(\mathrm{OH})_2(s) \longrightarrow$

SK

Sara Kolms

Numerade Educator

Problem 35

Balance the following equations and write the corresponding ionic and net ionic equations (if appropriate):
(a) $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2(a q)+\mathrm{KOH}(a q) \longrightarrow$
(b) $\mathrm{H}_2 \mathrm{CO}_3(a q)+\mathrm{NaOH}(a q) \longrightarrow$
(c) $\mathrm{HNO}_3(a q)+\mathrm{Ba}(\mathrm{OH})_2(a q) \longrightarrow$

Himanshu Garg

Numerade Educator

Problem 36

Give an example of a redox reaction that is (a) a combination reaction, (b) a decomposition reaction, (c) a displacement reaction, and (d) a disproportionation reaction.

SK

Sara Kolms

Numerade Educator

Problem 37

What is an oxidation number? How is it used to identify redox reactions?

SK

Sara Kolms

Numerade Educator

Problem 38

Explain how oxidation number is different from charge or partial charge. Explain under what circumstances it is the same.

Keenan Mintz

University of Miami

Problem 39

Describe how the activity series is organized, and how it is used to make predictions about redox reactions.

SK

Sara Kolms

Numerade Educator

Problem 40

Use the following reaction to define the terms redox reaction, half-reaction, oxidizing agent, and reducing agent:
$$
4 \mathrm{Na}(\mathrm{~s})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{Na}_2 \mathrm{O}(\mathrm{~s})
$$

Himanshu Garg

Numerade Educator

Problem 41

Is it possible to have a reaction in which oxidation occurs and reduction does not? Explain.

SK

Sara Kolms

Numerade Educator

Problem 42

For the complete redox reactions represented here, write the half-reactions and identify the oxidizing and reducing agents:
(a) $4 \mathrm{Fe}+3 \mathrm{O}_2 \longrightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3$
(b) $\mathrm{Cl}_2+2 \mathrm{NaBr} \longrightarrow 2 \mathrm{NaCl}+\mathrm{Br}_2$
(c) $\mathrm{Si}+2 \mathrm{~F}_2 \longrightarrow \mathrm{SiF}_4$
(d) $\mathrm{H}_2+\mathrm{Cl}_2 \longrightarrow 2 \mathrm{HCl}$

Himanshu Garg

Numerade Educator

Problem 43

For the complete redox reactions represented here, break down each reaction into its half-reactions, identify the oxidizing agent, and identify the reducing agent.
(a) $2 \mathrm{Sr}+\mathrm{O}_2 \longrightarrow 2 \mathrm{SrO}$
(b) $2 \mathrm{Li}+\mathrm{H}_2 \longrightarrow 2 \mathrm{LiH}$
(c) $2 \mathrm{Cs}+\mathrm{Br}_2 \longrightarrow 2 \mathrm{CsBr}$
(d) $3 \mathrm{Mg}+\mathrm{N}_2 \longrightarrow \mathrm{Mg}_3 \mathrm{~N}_2$

Himanshu Garg

Numerade Educator

Problem 44

Phosphorus forms a variety of oxoacids. Indicate the oxidation number of phosphorus in each of the following acids: (a) $\mathrm{HPO}_3$, (b) $\mathrm{H}_3 \mathrm{PO}_2$, (c) $\mathrm{H}_3 \mathrm{PO}_3$, (d) $\mathrm{H}_3 \mathrm{PO}_4$, (e) $\mathrm{H}_4 \mathrm{P}_2 \mathrm{O}_7$, (f) $\mathrm{H}_5 \mathrm{P}_3 \mathrm{O}_{10}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 45

Arrange the following species in order of increasing oxidation number of the sulfur atom: (a) $\mathrm{H}_2 \mathrm{~S}$, (b) $\mathrm{S}_8$, (c) $\mathrm{H}_2 \mathrm{SO}_4$,
(d) $\mathrm{S}^{2-}$,
(e) $\mathrm{HS}^{-}$,
(f) $\mathrm{SO}_2$,
(g) $\mathrm{SO}_3$.

SK

Sara Kolms

Numerade Educator

Problem 46

Give the oxidation number for the following species: $\mathrm{H}_2, \mathrm{Se}_3, \mathrm{P}_4, \mathrm{O}, \mathrm{U}, \mathrm{As}_4, \mathrm{~B}_{12}$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 47

Give the oxidation numbers for the underlined atoms in the following molecules and ions: (a) ClF , (b) $\mathrm{IF}_7$ (c) $\mathrm{CH}_4$, (d) $\underline{\mathrm{C}}_2 \mathrm{H}_2$, (e) $\underline{\mathrm{C}}_2 \mathrm{H}_4$, (f) $\mathrm{K}_2 \mathrm{CrO}_4$, (g) $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$, (h) $\mathrm{KMnO}_4$, (i) $\mathrm{NaHCO}_3$, (j) $\mathrm{Li}_2$, (k) $\mathrm{NaIO}_3$, (l) $\mathrm{KO}_2$, (m) $\mathrm{PF}_6^{-}$, (n) $\mathrm{KAuCl}_4$.

Himanshu Garg

Numerade Educator

Problem 48

Give the oxidation numbers for the underlined atoms in the following molecules and ions: (a) $\mathrm{Mg}_3 \underline{\mathrm{~N}}_2$, (b) $\mathrm{Cs} \underline{\mathrm{O}}_2$,
(c) $\mathrm{CaC}{ }_2$,
(d) $\mathrm{CO}_3^{2-}$,
(e) ${\underset{\mathrm{C}}{2}}^{\mathrm{O}_4^{2-}}$,
(f) $\mathrm{Zn} \underline{\mathrm{O}}_2^{2-}$,
(g) $\mathrm{NaB} \mathrm{H}_4$. (h) $\mathrm{WO}_4^{2-}$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 49

Give the oxidation numbers for the underlined atoms in the following molecules and ions: (a) $\mathrm{Cs}_2 \mathrm{O}$, (b) $\mathrm{CaI}_2$,
(c) $\mathrm{Al}_2 \mathrm{O}_3$,
(d) $\mathrm{H}_3 \mathrm{AsO}_3$,
(e) $\mathrm{TiO}_2$, (f), $\mathrm{MoO}_4^{2-}$,
(g) $\mathrm{PcCl}_4^{2-}$,
(h) $\mathrm{PtCl}_6^{2-}$
(i) $\mathrm{SnF}_2$, (j) $\mathrm{ClF}_3$,
(k) $\mathrm{SbF}_6^{-}$.

Himanshu Garg

Numerade Educator

Problem 50

Determine which of the following metals can react with water: (a) Au , (b) Li , (c) Hg , (d) Ca , (e) Pl.

Himanshu Garg

Numerade Educator

Problem 51

Nitric acid is a strong oxidizing agent. State which of the following species is least likely to be produced when nitric acid reacts with a strong reducing agent such as zinc metal, and explain why: $\mathrm{N}_2 \mathrm{O}, \mathrm{NO}, \mathrm{NO}_2$, $\mathrm{N}_2 \mathrm{O}_4, \mathrm{~N}_2 \mathrm{O}_5, \mathrm{NH}_4^{+}$.

Himanshu Garg

Numerade Educator

Problem 52

Predict the outcome of the reactions represented by the following equations by using the activity series, and balance the equations.
(a)
$\mathrm{Cu}(s)+\mathrm{HCl}(a q) \longrightarrow$
(b)
$\mathrm{Au}(s)+\mathrm{NaBr}(a q) \longrightarrow$
(c)
$\mathrm{Mg}(s)+\mathrm{CuSO}_4(a q) \longrightarrow$
(d) $\mathrm{Zn}(s)+\mathrm{KBr}(a q) \longrightarrow$

Himanshu Garg

Numerade Educator

Problem 53

One of the following oxides does not react with molecular oxygen: $\mathrm{NO}, \mathrm{N}_2 \mathrm{O}, \mathrm{SO}_2, \mathrm{SO}_3, \mathrm{P}_4 \mathrm{O}_6$. Based on oxidation numbers, which one is it? Explain.

Himanshu Garg

Numerade Educator

Problem 54

Classify the following redox reactions as combination, decomposition, displacement, and/or disproportionation:
(a) $\mathrm{P}_4+10 \mathrm{Cl}_2 \longrightarrow 4 \mathrm{PCl}_5$
(b) $2 \mathrm{NO} \longrightarrow \mathrm{N}_2+\mathrm{O}_2$
(c) $\mathrm{Cl}_2+2 \mathrm{KI} \longrightarrow 2 \mathrm{KCl}+\mathrm{I}_2$
(d) $3 \mathrm{HNO}_2 \longrightarrow \mathrm{HNO}_3+\mathrm{H}_2 \mathrm{O}+2 \mathrm{NO}$

Himanshu Garg

Numerade Educator

Problem 55

Classify the following redox reactions as combination, decomposition, displacement, and/or disproportionation:
(a) $2 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{H}_2 \mathrm{O}+\mathrm{O}_2$
(b) $\mathrm{Mg}+2 \mathrm{AgNO}_3 \longrightarrow \mathrm{Mg}\left(\mathrm{NO}_3\right)_2+2 \mathrm{Ag}$
(c) $\mathrm{NH}_4 \mathrm{NO}_2 \longrightarrow \mathrm{~N}_2+2 \mathrm{H}_2 \mathrm{O}$
(d) $\mathrm{H}_2+\mathrm{Br}_2 \longrightarrow 2 \mathrm{HBr}$

Himanshu Garg

Numerade Educator

Problem 56

Write the equation for calculating molarity. Why is molarity a convenient concentration unit in chemistry?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 57

Describe the steps involved in preparing a solution of known molar concentration using a volumetric flask.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 58

Describe the basic steps involved in diluting a solution of known concentration.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 59

Write the equation that enables us to calculate the concentration of a diluted solution. Give units for all the terms.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 60

Describe how you would prepare 250 mL of a 0.707 M $\mathrm{NaNO}_3$ solution.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 61

Calculate the mass of KI in grams required to prepare $5.00 \times 10^2 \mathrm{~mL}$ of a 2.80 M solution.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 62

How many grams of KOH are present in 35.0 mL of a $5.50 M \mathrm{KOH}$ solution?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 63

How many moles of $\mathrm{MgCl}_2$ are present in 60.0 mL of a $0.100 \mathrm{M} \mathrm{MgCl}_2$ solution?

Himanshu Garg

Numerade Educator

Problem 64

Calculate the molarity of each of the following solutions: (a) 6.57 g of methanol $\left(\mathrm{CH}_3 \mathrm{OH}\right)$ in $1.50 \times 10^2 \mathrm{~mL}$ of solution, (b) 10.4 g of calcium chloride ( $\mathrm{CaCl}_2$ ) in $2.20 \times 10^2 \mathrm{~mL}$ of solution, (c) 7.82 g of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{\mathrm{g}}\right)$ in 85.2 mL of benzene solution.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 65

Calculate the molarity of each of the following solutions: (a) 29.0 g of ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$ in 545 mL of solution, (b) 15.4 g of sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ in 74.0 mL of solution, (c) 9.00 g of sodium chloride ( NaCl ) in 86.4 mL of solution.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 66

Determine how many grams of each of the following solutes would be needed to make $2.50 \times 10^2 \mathrm{~mL}$ of a $0.100-\mathrm{M}$ solution: (a) cesium iodide ( CsI ), (b) sulfuric acid $\left(\mathrm{H}_2 \mathrm{SO}_4\right)$, (c) sodium carbonate ( $\mathrm{Na}_2 \mathrm{CO}_3$ ), (d) potassium dichromate $\left(\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7\right)$, (e) potassium permanganate $\left(\mathrm{KMnO}_4\right)$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 67

Calculate the volume in milliliters of a solution required to provide the following: (a) 2.14 g of sodium chloride from a $0.270-\mathrm{M}$ solution, (b) 4.30 g of ethanol from a $1.50-M$ solution, (c) 0.85 g of acetic acid ( $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$ ) from a $0.30-M$ solution.

Himanshu Garg

Numerade Educator

Problem 68

Which best represents the before-and-after molecularlevel view of the dilution of a concentrated stock solution?

Freddie Montague

Freddie Montague

Numerade Educator

Problem 69

Which best represents an aqueous solution of sodium sulfate?

Lottie Adams

Numerade Educator

Problem 70

Water is added to 25.0 mL of a $0.866 M \mathrm{KNO}_3$ solution until the volume of the solution is exactly 500 mL . What is the concentration of the final solution?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 71

Describe how to prepare 1.00 L of a 0.646 M HCl solution, starting with a 2.00 M HCl solution.

Himanshu Garg

Numerade Educator

Problem 72

You have 505 mL of a $0.125 M \mathrm{HCl}$ solution and you want to dilute it to exactly 0.100 M . How much water should you add?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 73

How would you prepare 60.0 mL of $0.200 M \mathrm{HNO}_3$ from a stock solution of $4.00 M \mathrm{HNO}_3$ ?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 74

A volume of 46.2 mL of a 0.568 M calcium nitrate $\left[\mathrm{Ca}\left(\mathrm{NO}_3\right)_2\right]$ solution is mixed with 80.5 mL of a 1.396 M calcium nitrate solution. Calculate the concentration of the final solution.

Himanshu Garg

Numerade Educator

Problem 75

A volume of 35.2 mL of a $1.66 M \mathrm{KMnO}_4$ solution is mixed with 16.7 mL of a $0.892 M \mathrm{KMnO}_4$ solution. Calculate the concentration of the final solution.

Himanshu Garg

Numerade Educator

Problem 76

The maximum level of fluoride that the EPA allows in U.S. drinking water is $4 \mathrm{mg} / \mathrm{L}$. Convert this concentration to molarity.

Himanshu Garg

Numerade Educator

Problem 77

According to the website labtestsonline.org, a fasting blood sugar (glucose, $\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6$ ) level of at least 126 milligrams per deciliter ( $\mathrm{mg} / \mathrm{dL}$ ) can indicate Type 2 diabetes. Convert this concentration to molarity.

Himanshu Garg

Numerade Educator

Problem 78

(a) What is the $\mathrm{Na}^{+}$concentration in each of the following solutions: $3.25 M$ sodium sulfate, $1.78 M$ sodium carbonate, 0.585 M sodium bicarbonate? (b) What is the concentration of a lithium carbonate solution that is $0.595 M$ in $\mathrm{Li}^{+}$?

Sima Sarker

Numerade Educator

Problem 79

(a) Determine the chloride ion concentration in each of the following solutions: $0.150 M \mathrm{BaCl}_2, 0.566 M \mathrm{NaCl}, 1.202 \mathrm{M} \mathrm{AlCl}_3$. (b) What is the concentration of a $\mathrm{Sr}\left(\mathrm{NO}_3\right)_2$ solution that is 2.55 M in nitrate ion?

David Collins

Numerade Educator

Problem 80

What volume of 0.112 M ammonium sulfate contains 5.75 g of ammonium ion?

Dylan Gunawardene

Dylan Gunawardene

Numerade Educator

Problem 81

Determine the resulting nitrate ion concentration when 95.0 mL of $0.992 M$ potassium nitrate and 155.5 mL of $1.570 M$ calcium nitrate are combined.

Himanshu Garg

Numerade Educator

Problem 82

Absorbance values for five standard solutions of a colored solute were determined at 410 nm with a $1.00-\mathrm{cm}$ path length, giving the following table of data:
$$
\begin{array}{cc}
\text { Solute concentration }(\boldsymbol{M}) & \boldsymbol{A} \\
\hline 0.250 & 0.165 \\
0.500 & 0.317 \\
0.750 & 0.510 \\
1.000 & 0.650 \\
1.250 & 0.837
\end{array}
$$
The absorbance of a solution of unknown concentration containing the same solute was 0.400 . What is the concentration of the unknown solution? (See page 338.)

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Problem 83

Referring to Problem 9.82, (a) determine the absorbance values you would expect for solutions with the following concentrations: $0.4 M, 0.6 M, 0.8 M, 1.1 M$. (b) Using data in the table in Problem 9.82 , calculate the average molar absorptivity of the compound and determine the units of molar absorptivity. (See page 338.)

Tianyu Li

Numerade Educator

Problem 84

Describe the basic steps involved in gravimetric analysis. How does this procedure help us determine the identity of a compound or the purity of a compound if its formula is known?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 85

Explain why distilled water must be used in the gravimetric analysis of chlorides.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 86

Describe the basic steps involved in an acid-base titration. Why is this technique of great practical value?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 87

How does an acid-base indicator work?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 88

A student carried out two titrations using an NaOH solution of unknown concentration in the burette. In one titration she weighed out 0.2458 g of KHP (see page 343 ) and transferred it to an Erlenmeyer flask. She then added 20.00 mL of distilled water to dissolve the acid. In the other titration she weighed out 0.2507 g of KHP but added 40.00 mL of distilled water to dissolve the acid. Assuming no experimental error, would she obtain the same result for the concentration of the NaOH solution?

Himanshu Garg

Numerade Educator

Problem 89

Would the volume of a $0.10 M \mathrm{NaOH}$ solution needed to titrate 25.0 mL of a $0.10 M \mathrm{HNO}_2$ (a weak acid) solution be different from that needed to titrate 25.0 mL of a 0.10 M HCl (a strong acid) solution?

Lottie Adams

Numerade Educator

Problem 90

Which of the following best represents the contents of a beaker in which equal volumes of $0.10 M \mathrm{BaCl}_2$ and $0.10 M \mathrm{AgNO}_3$ were combined?

David Collins

Numerade Educator

Problem 91

Which of the following best represents the contents of a beaker in which equal volumes of 0.10 M NaCl and $0.10 M \mathrm{~Pb}\left(\mathrm{NO}_3\right)_2$ were combined?

Mary Shields

Numerade Educator

Problem 92

A sample of 0.6760 g of an unknown compound containing barium ions ( $\mathrm{Ba}^{2+}$ ) is dissolved in water and treated with an excess of $\mathrm{Na}_2 \mathrm{SO}_4$. If the mass of the $\mathrm{BaSO}_4$ precipitate formed is 0.4105 g , what is the percent by mass of Ba in the original unknown compound?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 93

If 30.0 mL of $0.150 \mathrm{M} \mathrm{CaCl}_2$ is added to 15.0 mL of $0.100 M \mathrm{AgNO}_3$, what is the mass in grams of AgCl precipitate?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 94

Diagram (a) shows a solution of a base and an acid before the neutralization reaction. Each of the after-reaction diagrams, (b)-(d), shows the products of reaction with one of the following acids: $\mathrm{HCl}, \mathrm{H}_2 \mathrm{SO}_4, \mathrm{H}_3 \mathrm{PO}_4$. Determine which diagram corresponds to which acid. Blue spheres $=\mathrm{OH}^{-}$ions, red spheres $=$ acid molecules, green spheres $=$ anions of the acids. Assume all the acid-base neutralization reactions go to completion.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 95

Diagram (a) shows a solution of HCl and a base before the neutralization reaction. Of diagrams (b)-(d), which represents the products of reaction when the base is sodium hydroxide and which represents the products when the base is barium hydroxide? Blue spheres $=$ base, red spheres $=\mathrm{H}^{+}$, grey spheres $=$ cations of the bases. Assume all the acid-base neutralization reactions go to completion.

Crystal Wang

Numerade Educator

Problem 96

The concentration of $\mathrm{Cu}^{2+}$ ions in the water (which also contains sulfate ions) discharged from a certain industrial plant is determined by adding excess sodium sulfide $\left(\mathrm{Na}_2 \mathrm{~S}\right)$ solution to 0.800 L of the water. The molecular equation is

$$
\mathrm{Na}_2 \mathrm{~S}(a q)+\mathrm{CuSO}_4(a q) \longrightarrow \mathrm{Na}_2 \mathrm{SO}_4(a q)+\mathrm{CuS}(a q)
$$

Write the net ionic equation and calculate the molar concentration of $\mathrm{Cu}^{2+}$ in the water sample if 0.0177 g of solid CuS is formed.

Himanshu Garg

Numerade Educator

Problem 97

How many grams of NaCl are required to precipitate most of the Ag ions from $2.50 \times 10^2 \mathrm{~mL}$ of a $0.0113 M \mathrm{AgNO}_3$ solution? Write the net ionic equation for the reaction.

Himanshu Garg

Numerade Educator

Problem 98

Calculate the concentration (in molarity) of an NaOH solution if 25.0 mL of the solution is needed to neutralize 17.4 mL of a $0.312 M \mathrm{HCl}$ solution.

Himanshu Garg

Numerade Educator

Problem 99

A quantity of 18.68 mL of a KOH solution is needed to neutralize 0.4218 g of KHP. What is the concentration (in molarity) of the KOH solution?

Marietjie Lutz

Numerade Educator

Problem 100

Determine the volume of 0.500 M HCl needed to neutralize each of the following:
(a) 10.0 mL of a $0.300 M \mathrm{NaOH}$ solution
(b) 10.0 mL of a $0.200 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_2$ solution

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 101

Calculate the volume in milliliters of a $1.420 M \mathrm{NaOH}$ solution required to titrate the following solutions:
(a) 25.00 mL of a 2.430 M HCl solution
(b) 25.00 mL of a $4.500 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4$ solution
(c) 25.00 mL of a $1.500 \mathrm{M} \mathrm{H}_3 \mathrm{PO}_4$ solution

Himanshu Garg

Numerade Educator

Problem 102

Oxygen $\left(\mathrm{O}_2\right)$ and carbon dioxide $\left(\mathrm{CO}_2\right)$ are colorless and odorless gases. Suggest two chemical tests that would allow you to distinguish between these two gases.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 103

Which of the following aqueous solutions would you expect to be the best conductor of electricity at $25^{\circ} \mathrm{C}$ ? Explain your answer.
(a) 0.20 M NaCl
(b) $0.60 \mathrm{MHC}_2 \mathrm{H}_3 \mathrm{O}_2$
(c) 0.25 M HCl
(d) $0.20 M \mathrm{Mg}\left(\mathrm{NO}_3\right)_2$

Himanshu Garg

Numerade Educator

Problem 104

A $5.00 \times 10^2 \mathrm{~mL}$ sample of 2.00 M HCl solution is treated with 4.47 g of magnesium. Calculate the concentration of the acid solution after all the metal has reacted. Assume that the volume remains unchanged.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 105

Calculate the volume of a $0.156 M \mathrm{CuSO}_4$, solution that would react with 7.89 g of zinc.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 106

Sodium carbonate ( $\mathrm{Na}_2 \mathrm{CO}_3$ ) is available in very pure form and can be used to standardize acid solutions. What is the molarity of an HCl solution if 28.3 mL of the solution is required to react with $0.256 \mathrm{~g}_{\text {of }} \mathrm{Na}_2 \mathrm{CO}_3$ ?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 107

Identify each of the following compounds as a nonelectrolyte, a weak electrolyte, or a strong electrolyte: (a) ethanolamine ( $\mathrm{H}_2 \mathrm{NC}_2 \mathrm{H}_4 \mathrm{OH}$ ), (b) potassium fluoride ( KF ), (c) ammonium nitrate ( $\mathrm{NH}_4 \mathrm{NO}_3$ ), (d) isopropanol ( $\mathrm{C}_3 \mathrm{H}_4 \mathrm{OH}$ ).

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 108

Identify each of the following compounds as a nonelectrolyte, a weak electrolyte, or a strong electrolyte: (a) lactose ( $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$ ), (b) lactic acid $\left(\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_2\right)$, (c) dimethylamine $\left[\left(\mathrm{CH}_3\right)_2 \mathrm{NH}\right]$, (d) barium hydraxide $\left[\mathrm{Ba}(\mathrm{OH})_2\right]$.

Himanshu Garg

Numerade Educator

Problem 109

Determine the predominant species (there may be more than one) in an aqueous solution for each of the compounds in Problem 9.107.

Himanshu Garg

Numerade Educator

Problem 110

Determine the predominant species (there may be more than one) in an aqueous solution for each of the compounds in Problem 9.108.

Himanshu Garg

Numerade Educator

Problem 111

A $3.664-\mathrm{g}$ sample of a monoprotic acid was dissolved in water. It took 20.27 mL of a 0.1578 M NaOH solution to neutralize the acid. Calculate the molar mass of the acid.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 112

Acetic acid ( $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$ ) is an important ingredient of vinegar. A sample of 50.0 mL of a commercial vinegar is titrated against a 1.00 M NaOH solution. What is the concentration (in $M$ ) of acetic acid present in the vinegar if 5.75 mL of the buse is needed for the titration?

Himanshu Garg

Numerade Educator

Problem 113

A $15.00-\mathrm{mL}$ solution of potassium nitrate $\left(\mathrm{KNO}_3\right)$ was diluted to 125.0 mL , and 25.00 mL of this solution was then diluted to $1.000 \times 10^2 \mathrm{~mL}$. The concentration of the final solution is 0.00383 M . Calculate the concentration of the original solution.

Tom Comey

Numerade Educator

Problem 114

When 2.50 g of a zinc strip was placed in an $\mathrm{AgNO}_3$ solution, silver metal formed on the surface of the strip. After some time had passed, the strip was removed from the solution, dried, and weighed. If the mass of the strip was 3.37 g , calculate the mass of Ag and Zn metals present.

Himanshu Garg

Numerade Educator

Problem 115

Calculate the mass of the precipitate formed when 2.27 L of $0.0820 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_2$ is mixed with 3.06 L of $0.0664 M \mathrm{Na}_2 \mathrm{SO}_{\mathrm{c}}$.

Lottie Adams

Numerade Educator

Problem 116

What is the oxidation number of O in HFO ?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 117

Classify the following reactions according to the types discussed in the chapter:
(a) $\mathrm{Cl}_2+2 \mathrm{OH}^{-} \longrightarrow \mathrm{Cl}+\mathrm{ClO}^{-}+\mathrm{H}_2 \mathrm{O}$
(b) $\mathrm{Ca}^{2+}+\mathrm{CO}_3^{2-} \longrightarrow \mathrm{CaCO}_3$
(c) $\mathrm{NH}_2+\mathrm{H}^{+} \longrightarrow \mathrm{NH}_4^{-}$
(d) $2 \mathrm{CCl}_4+\mathrm{CrO}_4^{2-} \longrightarrow 2 \mathrm{COCl}_2+\mathrm{CrO}_2 \mathrm{Cl}_2+2 \mathrm{Cl}$
(e) $\mathrm{Ca}+\mathrm{F}_2 \longrightarrow \mathrm{CaF}_2$
(f) $2 \mathrm{Li}+\mathrm{H}_2 \longrightarrow 2 \mathrm{LiH}$
(g) $\mathrm{Ba}\left(\mathrm{NO}_3\right)_2+\mathrm{Na}_2 \mathrm{SO}_4 \longrightarrow 2 \mathrm{NaNO}_3+\mathrm{BaSO}_4$
(h) $\mathrm{CuO}+\mathrm{H}_2 \longrightarrow \mathrm{Cu}+\mathrm{H}_2 \mathrm{O}$
(i) $\mathrm{Zn}+2 \mathrm{HCl} \longrightarrow \mathrm{ZnCl}_2+\mathrm{H}_2$
(j) $2 \mathrm{FeCl}_2+\mathrm{Cl}_2 \longrightarrow 2 \mathrm{FeCl}_3$

Himanshu Garg

Numerade Educator

Problem 118

Calculate the concentration of the acid (or base) remaining in solution when 10.7 mL . of $0.211 M \mathrm{HNO}_3$ is added to 16.3 mL of 0.258 M NaOH .

Himanshu Garg

Numerade Educator

Problem 119

(a) Describe a preparation for magnesium hydroxide $\left[\mathrm{Mg}(\mathrm{OH})_2\right]$ and predict its solubility. (b) Milk of magnesia contains mostly $\mathrm{Mg}(\mathrm{OH})_2$, and is effective in treating acid (mostly hydrochloric acid) indigestion. Calculate the volume of a 0.035 M HCl solution (a typical acid concentration in an upset stomach) needed to react with two spoonfuls (approximately 10 mL ) of milk of magnesia [at $0.080 \mathrm{~g} \mathrm{Mg}(\mathrm{OH})_2 / \mathrm{mL}$ ].

Himanshu Garg

Numerade Educator

Problem 120

A quantitative definition of solubility is the number of grams of a solute that will dissolve in a given volume of water at a particular temperature. Describe an experiment that would enable you to determine the solubility of a soluble compound.

Himanshu Garg

Numerade Educator

Problem 121

A $60.0-\mathrm{mL} 0.513 M$ glucose $\left(\mathrm{C}_4 \mathrm{H}_{22} \mathrm{O}_4\right)$ solution is mixed with 120.0 mL of a 2.33 M glucose solution. What is the concentration of the final solution? Assume the volumes are additive.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 122

An ionic compound X is only slightly soluble in water. What test would you employ to show that the compound does indeed dissolve in water to a certain extent?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 123

You are given a colorless liquid. Describe three chemical tests you would perform on the liquid to show that it is water.

David Collins

Numerade Educator

Problem 124

Using the apparatus shown in Figure 9.1, a student found that a sulfuric acid solution caused the lightbulb to glow brightly. However, after the addition of a certain amount of a barium hydroxide $\left[\mathrm{Ba}(\mathrm{OH})_2\right]$ solution, the light began to dim even though $\mathrm{Ba}(\mathrm{OH})_2$ is also a strong electrolyte. Explain.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 125

Which of the diagrams shown corresponds to the reaction between $\mathrm{AgOH}_{(\mathrm{s})}$ and $\mathrm{HNO}_3$ (aq)? Write a balanced equation for the reaction. (For simplicity, water molecules are not shown.)

Himanshu Garg

Numerade Educator

Problem 126

Which of the diagrams shown corresponds to the reaction between $\mathrm{Ba}(\mathrm{OH})_2(\mathrm{aq})$ and $\mathrm{H}_2 \mathrm{SO}_4(\mathrm{aq})$ ? Write a balanced equation for the reaction. (For simplicity, water molecules are not shown.)

Himanshu Garg

Numerade Educator

Problem 127

You are given a soluble compound of an unknown molecular formula.
(a) Describe three tests that would show that the compound is an acid.
(b) Once you have established that the compound is an acid, describe how you would determine its molar mass using an NaOH solution of known concentration. (Assume the acid is monoprotic.)
(c) How would you find out whether the acid is weak or strong? You are provided with a sample of NaCl and an apparatus like that shown in Figure 9.1 for comparison.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 128

You are given two colorless solutions, one containing NaCl and the other sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_n\right)$. Suggest a chemical and a physical test that would allow you to distinguish between these two solutions.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 129

The concentration of lead ions $\left(\mathrm{Pb}^{2+}\right)$ in a sample of polluted water that also contains nitrate ions ( $\mathrm{NO}_2$ ) is determined by adding solid sodium sulfate ( $\mathrm{Na}_2 \mathrm{SO}_4$ ) to exactly 500 mL of the water. (a) Write the molecular and net ionic equations for the reaction. (b) Calculate the molar concentration of $\mathrm{Pb}^{2+}$ if $0.00450 \mathrm{~g} \mathrm{~g}^{\circ} \mathrm{Na}_2 \mathrm{SO}_4$ was needed for the complete precipitation of $\mathrm{Pb}^{2+}$ ions as $\mathrm{PbSO}_c$

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 130

Hydrochloric acid is not an oxidizing agent in the sense that sulfuric acid and nitric acid are. Explain why the chloride ion is not a strong oxidizing agent like $\mathrm{SO}_4^{2-}$ and $\mathrm{NO}_3^{-}$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 131

Explain how you would prepare potassium iodide (KI) by means of (a) an acid-buse reaction and (b) a reaction between an acid and a carbonate compound.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 132

Sodium reacts with water to yield hydrogen gas. Why is this reaction not used in the laboratory preparation of hydrogen?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 133

Describe how you would prepare the following compounds: (a) $\mathrm{Mg}(\mathrm{OH})_2$, (b) AgI , (c) $\mathrm{Ba}_3\left(\mathrm{PO}_4\right)_2$.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 134

Someone spilled concentrated sulfuric acid on the floor of a chemistry laboratory. To neutralize the acid, would it be preferable to pour concentrated sodium hydroxide solution or spray solid sodium bicarbonate over the acid? Explain your choice and the chemical basis for the action.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 135

Describe in each case how you would separate the cations or anions in the following aqueous solutions:
(a) $\mathrm{NaNO}_3$ and $\mathrm{Ba}\left(\mathrm{NO}_3\right)_2$, (b) $\mathrm{Mg}\left(\mathrm{NO}_3\right)_2$ and $\mathrm{KNO}_3$,
(c) KBr and $\mathrm{KNO}_3$, (d) $\mathrm{K}_2 \mathrm{PO}_4$ and $\mathrm{KNO}_3$, (c) $\mathrm{Na}_2 \mathrm{CO}_3$ and $\mathrm{NaNO}_v$.

Himanshu Garg

Numerade Educator

Problem 136

The following are common bousehold compounds: salt (NaCl), sugar (sucrose), vinegar (contains acetic acid, $\mathrm{HC}_2 \mathrm{H}_2 \mathrm{O}_2$ ), baking soda ( $\mathrm{NaHCO}_3$ ), washing soda $\left(\mathrm{Na}_2 \mathrm{CO}_3 \cdot 10 \mathrm{H}_2 \mathrm{O}\right)$, boric acid ( $\mathrm{H}_3 \mathrm{BO}_y$, used in eyewash), Epsom salts $\left(\mathrm{MgSO}_4 \cdot 7 \mathrm{H}_2 \mathrm{O}\right)$, sodium hydroxide (used in drain openers), ammonia, milk of magnesia $\left[\mathrm{Mg}(\mathrm{OH})_2\right]$, and calcium carbonate. Based on what you have learned in this chapter, describe tests that would allow you to identify each of these compounds.

Himanshu Garg

Numerade Educator

Problem 137

Sulfites (compounds containing the $\mathrm{SO}_3^{2-}$ ions) are used as preservatives in dried fruits and vegetables and in wine making. In an experiment to test for the presence of sulfite in fruit, a student first soaked several dried apricots in water overnight and then filtered the solution to remove all solid particles. She then treated the solution with hydrogen peraxide ( $\mathrm{H}_2 \mathrm{O}_2$ ) to oxidize the sulfite ions to sulfate ions. Finally, the sulfate ions were precipitated by treating the solution with a few drops of a barium chloride ( $\mathrm{BaCl}_2$ ) solution. Write a balanced equation for each of the preceding steps.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 138

A $0.8870-\mathrm{g}$ sample of a mixture of NaCl and KCl is dissolved in water, and the solution is then treated with an excess of $\mathrm{AgNO}_3$ to yield 1.913 g of AgCl . Calculate the percent by mass of each compound in the mixture.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 139

Chlorine forms a number of oxides with the following oxidation numbers: $+1,+3,+4,+6$, and +7 . Write a formula for each of these compounds.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 140

One of the uses of oxalic ( $\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4$ ) acid is rust removal. It reacts with rust ( $\mathrm{Fe}_2 \mathrm{O}_2$ ) according to the equation

$$
\begin{aligned}
\mathrm{Fe}_2 \mathrm{O}(x)+6 \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4(a q) \longrightarrow & - \\
& 2 \mathrm{Fe}_2\left(\mathrm{C}_2 \mathrm{O}_4\right)_3^2(a q)+3 \mathrm{H}_2 \mathrm{O}(l)+6 \mathrm{H}^{+}(a q)
\end{aligned}
$$

Calculate the number of grams of rust that can be removed by $5.00 \times 10^2 \mathrm{~mL}$ of a 0.100 M solution of oxalic acid.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 141

Acetylsalicylic acid ( $\mathrm{HC}_6 \mathrm{H}_2 \mathrm{O}_6$ ) is a monoprotic acid commonly known as "aspirin." A typical aspirin tablet, however, contains only a small amount of the acid. In an experiment to determine its composition, an aspirin tablet was crushed and dissolved in water. It took 12.25 mL of 0.1466 MNaOH to neutralize the solution. Calculate the number of grains of aspirin in the tablet (one grain $=0.0648 \mathrm{~g}$ ).

Himanshu Garg

Numerade Educator

Problem 142

$ \mathrm{~A} 0.9157-\mathrm{g}$ mixture of $\mathrm{CaBr}_2$ and NaBr is dissolved in water, and $\mathrm{AgNO}_3$ is added to the solution to form AgBr precipitate. If the mass of the precipitate is 1.6930 g , what is the percent by mass of NaBr in the original mixture?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 143

Hydrogen halides ( $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}, \mathrm{HI}$ ) are highly reactive compounds that have many industrial and laboratory uses. (a) In the laboratory, HF and HCl can be generated by reacting $\mathrm{CaF}_2$ and NaCl with concentrated sulfuric acid. Write appropriate equations for the reactions. (Hint: These are not redox reactions.) (b) Why is it that HBr and HI cannot be prepared similarly, that is, by reacting NaBr and NaI with concentrated sulfuric acid? (Hint: $\mathrm{H}_2 \mathrm{SO}_6$ is a stronger cxidizing agent than both $\mathrm{Br}_2$ and $\mathrm{I}_2$ ) (c) HBr can be prepared by combining phosphorus tribromide ( $\mathrm{PBr}_3$ ) with water. Write an equation for this reaction.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 144

A $325-\mathrm{mL}$ sample of solution contains 25.3 g of $\mathrm{CaCl}_2$. (a) Calculate the molar concentration of $\mathrm{Cl}^{-}$in this solution. (b) How many grams of $\mathrm{Cl}^{-}$are in 0.100 L of this solution?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 145

Phosphoric acid ( $\mathrm{H}_2 \mathrm{PO}_3$ ) is an important industrial chemical used in fertilizers, detergents, and the food industry. It is produced by two different methods. In the electric furnace method, elemental phosphorus ( $\mathrm{P}_4$ ) is burned in air to form $\mathrm{PO}_{\text {w }}$, which is then combined with water to give $\mathrm{H}_2 \mathrm{PO}_4$. In the wet process, the mineral phosphate rock $\left[\mathrm{Ca}_3\left(\mathrm{PO}_4\right), \mathrm{F}\right]$ is combined with sulfuric acid to give $\mathrm{H}_2 \mathrm{PO}_4$ (and HF and $\mathrm{CaSO}_3$ ). Write equations for these processes, and classify cach step as precipitation, acid-base, or redox reaction.

Himanshu Garg

Numerade Educator

Problem 146

Ammonium nitrate ( $\mathrm{NH}_6 \mathrm{NO}_2$ ) is one of the most important nitrogen-containing fertilizers. Its purity can be analyzed by titrating a solution of $\mathrm{NH}_4 \mathrm{NO}_3$ with a standard NaOH solution. In one experiment, a 0.2041 eg sample of industrially prepared $\mathrm{NH}_4 \mathrm{NO}_3$, required 24.42 mL of $0.1023 M \mathrm{NaOH}$ for neutralization. (a) Write a net ionic equation for the reaction. (b) What is the percent purity of the sample?

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 147

Potassium superoxide ( $\mathrm{KO}_2$ ) is used in some selfcontaining breathing equipment by firefighters. It reacts with carbon dixxide in respired (exhaled) air to form potassium carbonate and oxygen gas. (a) Write an equation for the reaction. (b) What is the oxidation number of oxygen in the $\mathrm{O}_2^{-}$ion? (c) How many liters of respired air can react with 7.00 g of $\mathrm{KO}_2$, if each liter of respired air contains $0.063 \mathrm{~g}^{\circ} \mathrm{gof}_2$ ?

Himanshu Garg

Numerade Educator

Problem 148

Barium sulfate ( $\mathrm{BaSO}_4$ ) has important medical uses. The dense salt absorbs X rays and acts as an opaque barrier. Thus, X -ray examination of a patient who has swallowed an aqueous suspension of $\mathrm{BaSO}_4$ particles allows the radiologist to diagnose an ailment of the patient's digestive tract. Given the following starting compounds, describe how you would prepare $\mathrm{BaSO}_4$ by neutralization and by precipitation: $\mathrm{Ba}(\mathrm{OH})_2, \mathrm{BaCl}_2$, $\mathrm{BaCO}_3, \mathrm{H}_2 \mathrm{SO}_8$ and $\mathrm{K}_2 \mathrm{SO}_4$.

Himanshu Garg

Numerade Educator

Problem 149

Is the following reaction a redox reaction? Explain.
$$
3 \mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{O}_2(\mathrm{~g})
$$

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 150

Absorbance values for five standard $\mathrm{KMnO}_4$ solutions were determined at a wavelength of 528 nm . The data are tabulated here.
$$
\begin{array}{cc}
\text { Solute concentration }(M) & \mathbf{A} \\
\hline 0.0500 & 0.172 \\
0.100 & 0.310 \\
0.150 & 0.502 \\
0.200 & 0.680 \\
0.250 & 0.822
\end{array}
$$
The absorbance of a $\mathrm{KMnO}_4$ solution with unknown concentration, analyzed under the same conditions, was 0.550 . Determine the concentration of the unknown solution. (See page 338.)

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Problem 151

Draw molecular models to represent the following acidbase reactions:
(a) $\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}^{+} \longrightarrow 2 \mathrm{H}_2 \mathrm{O}$
(b) $\mathrm{NH}_4^{+}+\mathrm{NH}_2^{-} \longrightarrow 2 \mathrm{NH}_3$

Identify the Brsinsted acid and base in each case.

David Collins

Numerade Educator

Problem 152

On standing, a concentrated nitric acid gradually turns yellow. Explain. (Hint: Nitric acid slowly decomposes. Nitrogen dicxide is a colored gas.)

Himanshu Garg

Numerade Educator

Problem 153

When preparing a solution of known concentration, explain why one must first dissolve the solid completely before adding enough solvent to fill the volumetric flask to the mark.

Himanshu Garg

Numerade Educator

Problem 154

Can the following decomposition reaction be characterized as an acid-buse reaction? Explain.

$$
\mathrm{NH}_2 \mathrm{Cl}(s) \longrightarrow \mathrm{NH}_3(g)+\mathrm{HCl}_{(g)}
$$

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 155

Give a chemical explanation for each of the following: (a) When calcium metal is added to a sulfuric acid solution, hydrogen gas is generated. After a few minutes, the reaction slows down and eventually stops even though mone of the reactants is used up. Explain. (b) In the activity series, aluminum is above hydrogen, yet the metal appears to be unreactive toward hydrochloric acid. Why? (Hint: Al forms an oxide, $\mathrm{Al}_2 \mathrm{O}_3$, on the surface.) (c) Sodium and potassium lie above copper in the activity series. Explain why $\mathrm{Cu}^{2+}$ ions in a $\mathrm{CuSO}_4$ solution are not converted to metallic copper upon the addition of these metals. (d) A metal M reacts slowly with steam. There is no visible change when it is placed in a pale green iron(II) sulfate solution. Where should we place M in the activity series? (e) Before aluminum metal was obtained by electrolysis, it was produced by reducing its chloride (AICI) with an active metal. What metals would you use to produce aluminum in that way?

Himanshu Garg

Numerade Educator

Problem 156

The recommended procedure for preparing a very dilute solution is not to weigh out a very small mass or measure a very small volume of a stock solution. Instead, it is done by serial dilution. A sample of 0.8214 g of $\mathrm{KMnO}_4$ was dissolved in water and made up to the volume in a $500-\mathrm{mL}$ volumetric flask. A $2.000-\mathrm{mL}$ sample of this solution was transferred to a 1000 mL volumetric flask and diluted to the mark with water. Next, 10.00 mL of the diluted solution was transferred to a $250-\mathrm{mL}$ flask and diluted to the mark with water. (a) Calculate the concentration (in molarity) of the final solution. (b) Calculate the mass of $\mathrm{KMnO}_4$ needed to directly prepare the final solution and comment on why dilute solutions are not typically prepared directly.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 157

The following "cycle of copper" experiment is performed in some general chemistry laboratories. The series of reactions starts with copper and ends with metallic copper. The steps are as followx: (1) A piece of copper wire of known mass is allowed to react with concentrated nitric acid [the products are copper(II) nitrate, nitrogen dioxide, and water]. (2) The copper(II) nitrate is treated with a sodium hydroxide solution to form copper(II) hydroxide precipitate. (3) On heating, copper(II) hydraxide decomposes to yield copper(II) oxide. (4) The copper(II) oxide is combined with concentrated sulfuric acid to yield copper(II) sulfate. (5) Copper(II) sulfate is treated with an excess of zinc metal to form metallic copper. (6) The remaining zinc metal is removed by treatment with hydrochloric acid, and metallic copper is filtered, dried, and weighed.
(a) Write a bulanced equation for each step and classify the reactions. (b) Assuming that a student started with 65.6 g of copper, calculate the theoretical yield at each step. (c) Considering the nature of the steps, comment on why it is possible to recover most of the copper used at the start.

Himanshu Garg

Numerade Educator

Problem 158

Use the periodic table framework given here to show the names and positions of two metals that can (a) displace hydrogen from cold water and (b) displace hydrogen from acid. (c) Also show two metals that do not react with either water or acid. Use trends in periodic properties to explain the differences in your answers to parts (a) and (b).

Himanshu Garg

Numerade Educator

Problem 159

A $22.02-\mathrm{mL}$ solution containing $1.615 \mathrm{~g} \mathrm{Mg}\left(\mathrm{NO}_3\right)_2$ is mixed with a $28.64-\mathrm{mL}$ solution containing 1.073 g NaOH . Calculate the concentrations of the ions remaining in solution affer the reaction is complete. Assume volumes are additive.

Kim Trang Nguyen

Kim Trang Nguyen

Numerade Educator

Problem 160

Because the acid-base and precipitation reactions discussed in this chapter all involve ionic species, their progress can be monitored by measuring the electrical conductance of the solution. Match each of the following reactions with one of the diagrams shown here. The electrical conductance is shorwn in arbitrary units. Explain the significance of the point at which the slope changes in each diagram.
(1) A 1.0 M KOH solution is added to 1.0 L of 1.0 M $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2-$
(2) A $1.0 M \mathrm{NaOH}$ solution is added to 1.0 L of 1.0 M HCl
(3) A $1.0 M \mathrm{BaCl}_2$ solution is added to 1.0 L of 1.0 M $\mathrm{K}_2 \mathrm{SO}_4$.
(4) A 1.0 M NaCl solution is added to 1.0 L of 1.0 M $\mathrm{AgNO}_3$.
(5) $\mathrm{A} 1.0 M \mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$ solution is added to 1.0 L of $1.0 \mathrm{MNH}_3$

Himanshu Garg

Numerade Educator