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Chemistry The Central Science

Theodore E. Brown, Theodore L. Brown, H. Eugene LeMaytion Compounds

Chapter 3

Stoichiometry: Caculations with Chemical Formulas and Equations - all with Video Answers

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Chapter Questions

00:43

Problem 1

The reaction between reactant A (blue spheres) and reactant $\mathrm{B}$ (red spheres) is shown in the following diagram:
Based on this diagram, which equation best describes the reaction? [Section 3.1]
(a) $\mathrm{A}_{2}+\mathrm{B} \longrightarrow \mathrm{A}_{2} \mathrm{~B}$
(b) $\mathrm{A}_{2}+4 \mathrm{~B} \longrightarrow 2 \mathrm{AB}_{2}$
(c) $2 \mathrm{~A}+\mathrm{B}_{4} \longrightarrow 2 \mathrm{AB}_{2}$
(d) $\mathrm{A}+\mathrm{B}_{2} \longrightarrow \mathrm{AB}_{2}$

Aadit Sharma
Aadit Sharma
Numerade Educator
03:03

Problem 2

Under appropriate experimental conditions, $\mathrm{H}_{2}$ and $\mathrm{CO}$ undergo a combination reaction to form $\mathrm{CH}_{3} \mathrm{OH}$. The following drawing represents a sample of $\mathrm{H}_{2}$. Make a corresponding drawing of the CO needed to react completely with the $\mathrm{H}_{2}$. How did you arrive at the number of CO molecules in your drawing? [Section 3.2]

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
00:58

Problem 3

The following diagram represents the collection of elements formed by a decomposition reaction. (a) If the blue spheres represent $\mathrm{N}$ atoms and the red ones represent $\mathrm{O}$ atoms, what was the empirical formula of the original compound? (b) Could you draw a diagram representing the molecules of the compound that had been decomposed? Why or why not? $[\operatorname{Section} 3.2]$

Aadit Sharma
Aadit Sharma
Numerade Educator
04:08

Problem 4

The following diagram represents the collection of $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ molecules formed by complete combustion of a hydrocarbon. What is the empirical formula of the hydrocarbon? $[$ Section 3.2$]$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
04:31

Problem 5

Glycine, an amino acid used by organisms to make proteins, is represented by the following molecular model.
(a) Write its molecular formula.
(b) Determine its molar mass.
(c) Calculate the mass of 3 moles of glycine.
(d) Calculate the percent nitrogen by mass in glycine. [Sections 3.3 and 3.5$]$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:29

Problem 6

The following diagram represents a high-temperature reaction between $\mathrm{CH}_{4}$ and $\mathrm{H}_{2} \mathrm{O} .$ Based on this reaction, how many moles of each product can be obtained starting with $4.0 \mathrm{~mol}$ $\mathrm{CH}_{4} ?[$ Section 3.6$]$

Narayan Hari
Narayan Hari
Numerade Educator
03:52

Problem 7

Nitrogen $\left(\mathrm{N}_{2}\right)$ and hydrogen $\left(\mathrm{H}_{2}\right)$ react to form ammonia $\left(\mathrm{NH}_{3}\right) .$ Consider the mixture of $\mathrm{N}_{2}$ and $\mathrm{H}_{2}$ shown in the accompanying diagram. The blue spheres represent $\mathrm{N},$ and the white ones represent $\mathrm{H}$. Draw a representation of the product mixture, assuming that the reaction goes to completion. How did you arrive at your representation? What is the limiting reactant in this case? [Section 3.7]

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
03:50

Problem 8

Nitrogen monoxide and oxygen react to form nitrogen dioxide. Consider the mixture of $\mathrm{NO}$ and $\mathrm{O}_{2}$ shown in the accompanying diagram. The blue spheres represent $\mathrm{N},$ and the red ones represent $\mathrm{O}$.
(a) Draw a representation of the product mixture, assuming that the reaction goes to completion. What is the limiting reactant in this case? (b) How many $\mathrm{NO}_{2}$ molecules would you draw as products if the reaction had a percent yield of $75 \% ?$ [Section 3.7]

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:53

Problem 9

(a) What scientific principle or law is used in the process of balancing chemical equations? (b) In balancing equations, why should you not change subscripts in chemical formulas?
(c) How would you write out liquid water, water vapor, aqueous sodium chloride, and solid sodium chloride in chemical equations?

Isabella Miller
Isabella Miller
Numerade Educator
05:52

Problem 10

(a) What is the difference between adding a subscript 2 to the end of the formula for $\mathrm{CO}$ to give $\mathrm{CO}_{2}$ and adding a coefficient in front of the formula to give $2 \mathrm{CO} ?$ (b) Is the following chemical equation, as written, consistent with the law of conservation of mass?
$$
\begin{aligned}
3 \mathrm{Mg}(\mathrm{OH})_{2}(s)+2 \mathrm{H}_{3} \mathrm{PO}_{4}(a q) \longrightarrow & \\
\mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2}(s)+6 \mathrm{H}_{2} \mathrm{O}(l)
\end{aligned}
$$
Why or why not?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
12:20

Problem 11

Balance the following equations:
(a) $\mathrm{CO}(g)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$
(b) $\mathrm{N}_{2} \mathrm{O}_{5}(g)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{HNO}_{3}(a q)$
(c) $\mathrm{CH}_{4}(g)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{CCl}_{4}(l)+\mathrm{HCl}(g)$
(d) $\mathrm{Al}_{4} \mathrm{C}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{Al}(\mathrm{OH})_{3}(s)+\mathrm{CH}_{4}(g)$
(e) $\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}_{2}(l)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(f) $\mathrm{Fe}(\mathrm{OH})_{3}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow$
$\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$
(g) $\mathrm{Mg}_{3} \mathrm{~N}_{2}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow$
$\mathrm{MgSO}_{4}(a q)+\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}(a q)$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
13:44

Problem 12

Balance the following equations:
(a) $\mathrm{Li}(s)+\mathrm{N}_{2}(g) \longrightarrow \mathrm{Li}_{3} \mathrm{~N}(s)$
(b) $\mathrm{TiCl}_{4}(l)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{TiO}_{2}(s)+\mathrm{HCl}(a q)$
(c) $\mathrm{NH}_{4} \mathrm{NO}_{3}(s) \longrightarrow \mathrm{N}_{2}(g)+\mathrm{O}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(d) $\mathrm{Ca}_{3} \mathrm{P}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(a q)+\mathrm{PH}_{3}(g)$
(e) $\mathrm{Al}(\mathrm{OH})_{3}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$
(f) $\mathrm{AgNO}_{3}(a q)+\mathrm{Na}_{2} \mathrm{CO}_{3}(a q) \longrightarrow \underset{\mathrm{Ag}_{2} \mathrm{NO}_{3}(s)+\mathrm{Na}_{2} \mathrm{CO}_{3}(a q)}{\longrightarrow} \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)+\mathrm{N}_{2}(g)$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
08:26

Problem 13

Write balanced chemical equations to correspond to each of the following descriptions: (a) Solid calcium carbide, $\mathrm{CaC}_{2}$, reacts with water to form an aqueous solution of calcium hydroxide and acetylene gas, $\mathrm{C}_{2} \mathrm{H}_{2}$. (b) When solid potassium chlorate is heated, it decomposes to form solid potassium chloride and oxygen gas. (c) Solid zinc metal reacts with sulfuric acid to form hydrogen gas and an aqueous solution of zinc sulfate. (d) When liquid phosphorus trichloride is added to water, it reacts to form aqueous phosphorous acid, $\mathrm{H}_{3} \mathrm{PO}_{3}(a q),$ and aqueous hydrochloric acid.
(e) When hydrogen sulfide gas is passed over solid hot iron(III) hydroxide, the resultant reaction produces solid iron(III) sulfide and gaseous water.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
11:30

Problem 14

Write balanced chemical equations to correspond to each of the following descriptions: (a) When sulfur trioxide gas reacts with water, a solution of sulfuric acid forms. (b) Boron sulfide, $\mathrm{B}_{2} \mathrm{~S}_{3}(s),$ reacts violently with water to form dissolved boric acid, $\mathrm{H}_{3} \mathrm{BO}_{3},$ and hydrogen sulfide gas.
(c) Phosphine, $\mathrm{PH}_{3}(g)$, combusts in oxygen gas to form water vapor and solid tetraphosphorus decaoxide. (d) When solid mercury(II) nitrate is heated, it decomposes to form solid mercury(II) oxide, gaseous nitrogen dioxide, and oxygen. (e) Copper metal reacts with hot concentrated sulfuric acid solution to form aqueous copper(II) sulfate, sulfur dioxide gas, and water.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
06:44

Problem 15

(a) When the metallic element sodium combines with the nonmetallic element bromine, $\mathrm{Br}_{2}(l),$ how can you determine the chemical formula of the product? How do you know whether the product is a solid, liquid, or gas at room temperature? Write the balanced chemical equation for the reaction.
(b) When a hydrocarbon burns in air, what reactant besides the hydrocarbon is involved in the reaction? What products are formed? Write a balanced chemical equation for the combustion of benzene, $\mathrm{C}_{6} \mathrm{H}_{6}(l),$ in air.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
04:57

Problem 16

(a) Determine the chemical formula of the product formed when the metallic element aluminum combines with the nonmetallic element bromine, $\mathrm{Br}_{2}$. Write the balanced chemical equation for the reaction. (b) What products form when a compound containing $\mathrm{C}, \mathrm{H},$ and $\mathrm{O}$ is completely combusted in air? Write a balanced chemical equation for the combustion of acetone, $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}(l),$ in air.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:15

Problem 17

Write a balanced chemical equation for the reaction that occurs when (a) $\mathrm{Mg}(s)$ reacts with $\mathrm{Cl}_{2}(g) ;$ (b) barium carbonate decomposes into barium oxide and carbon dioxide gas when heated; $(\mathbf{c})$ the hydrocarbon styrene, $\mathrm{C}_{8} \mathrm{H}_{8}(l)$, is combusted in air; (d) dimethylether, $\mathrm{CH}_{3} \mathrm{OCH}_{3}(g)$, is combusted in air.

Aadit Sharma
Aadit Sharma
Numerade Educator
06:41

Problem 18

Write a balanced chemical equation for the reaction that occurs when (a) calcium metal undergoes a combination reaction with $\mathrm{O}_{2}(g) ;$ (b) copper(II) hydroxide decomposes into copper(II) oxide and water when heated; (c) heptane, $\mathrm{C}_{7} \mathrm{H}_{16}(l),$ burns in air;
(d) methyl tert-butyl ether, $\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}(l)$ burns in air.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:21

Problem 19

Balance the following equations and indicate whether they are combination, decomposition, or combustion reactions:
(a) $\mathrm{C}_{3} \mathrm{H}_{6}(g)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(b) $\mathrm{NH}_{4} \mathrm{NO}_{3}(s) \longrightarrow \mathrm{N}_{2} \mathrm{O}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(c) $\mathrm{C}_{5} \mathrm{H}_{6} \mathrm{O}(l)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(d) $\mathrm{N}_{2}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{NH}_{3}(g)$
(e) $\mathrm{K}_{2} \mathrm{O}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{KOH}(a q)$

Aadit Sharma
Aadit Sharma
Numerade Educator
15:52

Problem 20

Balance the following equations and indicate whether they are combination, decomposition, or combustion reactions:
(a) $\mathrm{PbCO}_{3}(s) \longrightarrow \mathrm{PbO}(s)+\mathrm{CO}_{2}(g)$
(b) $\mathrm{C}_{2} \mathrm{H}_{4}(g)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(c) $\mathrm{Mg}(s)+\mathrm{N}_{2}(g) \longrightarrow \mathrm{Mg}_{3} \mathrm{~N}_{2}(s)$
(d) $\mathrm{C}_{7} \mathrm{H}_{8} \mathrm{O}_{2}(l)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(e) $\mathrm{Al}(s)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{AlCl}_{3}(s)$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
14:01

Problem 21

Determine the formula weights of each of the following com-
pounds: (a) nitric acid, $\mathrm{HNO}_{3} ;$ (b) $\mathrm{KMnO}_{4} ;$ (c) $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} ;$ (d) quartz, $\mathrm{SiO}_{2} ;$ (e) gallium sulfide, (f) chromium(III) sulfate, (g) phosphorus trichloride.

Vishal Sharma
Vishal Sharma
Numerade Educator
06:08

Problem 22

Determine the formula weights of each of the following compounds: (a) nitrous oxide, $\mathrm{N}_{2} \mathrm{O},$ known as laughing gas and used as an anesthetic in dentistry; (b) benzoic acid, $\mathrm{HC}_{7} \mathrm{H}_{5} \mathrm{O}_{2}$, a substance used as a food preservative; (c) $\mathrm{Mg}(\mathrm{OH})_{2}$, the active ingredient in milk of magnesia;
(d) urea, $\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}, \mathrm{a}$
compound used as a nitrogen fertilizer; (e) isopentyl acetate, $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{C}_{5} \mathrm{H}_{11}$, responsible for the odor of bananas.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:24

Problem 23

Calculate the percentage by mass of oxygen in the following compounds:
(a) morphine, $\quad \mathrm{C}_{17} \mathrm{H}_{19} \mathrm{NO}_{3}$;
(b) codeine, $\mathrm{C}_{18} \mathrm{H}_{21} \mathrm{NO}_{3} \quad$ (c) cocaine, $\mathrm{C}_{17} \mathrm{H}_{21} \mathrm{NO}_{4}$;
(d) tetracycline, $\mathrm{C}_{22} \mathrm{H}_{24} \mathrm{~N}_{2} \mathrm{O}_{8} ;$ (e) digitoxin, $\mathrm{C}_{41} \mathrm{H}_{64} \mathrm{O}_{13} ;$ (f) vancomycin,
$\mathrm{C}_{66} \mathrm{H}_{75} \mathrm{Cl}_{2} \mathrm{~N}_{9} \mathrm{O}_{24}$

Aadit Sharma
Aadit Sharma
Numerade Educator
11:54

Problem 25

Calculate the percentage by mass of the indicated element in the following compounds: (a) carbon in acetylene, $\mathrm{C}_{2} \mathrm{H}_{2},$ a gas used in welding; (b) hydrogen in ascorbic acid, $\mathrm{HC}_{6} \mathrm{H}_{7} \mathrm{O}_{6},$ also known as vitamin C; (c) hydrogen in ammonium sulfate, $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$, a substance used as a nitrogen fertilizer; (d) platinum in $\mathrm{PtCl}_{2}\left(\mathrm{NH}_{3}\right)_{2},$ a chemotherapy agent called cisplatin;
(e) oxygen in the female sex hormone estradiol, $\mathrm{C}_{18} \mathrm{H}_{24} \mathrm{O}_{2}$;
(f) carbon in capsaicin, $\mathrm{C}_{18} \mathrm{H}_{27} \mathrm{NO}_{3},$ the compound that gives the hot taste to chili peppers.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
10:22

Problem 26

Calculate the percentage of carbon by mass in each of the compounds represented by the following models:

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
01:31

Problem 27

(a) What is Avogadro's number, and how is it related to the mole? (b) What is the relationship between the formula weight of a substance and its molar mass?

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 28

(a) What is the mass, in grams, of a mole of ${ }^{12} \mathrm{C} ?$
(b) How many carbon atoms are present in a mole of ${ }^{12} \mathrm{C} ?$

Narayan Hari
Narayan Hari
Numerade Educator
02:17

Problem 29

Without doing any detailed calculations (but using a periodic table to give atomic weights), rank the following samples in order of increasing number of atoms: $0.50 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}$, $23 \mathrm{~g} \mathrm{Na}, 6.0 \times 10^{23} \mathrm{~N}_{2}$ molecules.

Narayan Hari
Narayan Hari
Numerade Educator
03:45

Problem 30

Without doing any detailed calculations (but using a periodic table to give atomic weights), rank the following samples in order of increasing number of atoms: $9.0 \times 10^{23}$ molecules of $\mathrm{H}_{2} \mathrm{O}_{2}, 2.0 \mathrm{~mol} \mathrm{CH}_{4}, 16 \mathrm{~g} \mathrm{O}_{2}$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:09

Problem 31

What is the mass, in kilograms, of an Avogadro's number of people, if the average mass of a person is $160 \mathrm{lb}$ ? How does this compare with the mass of Earth, $5.98 \times 10^{24} \mathrm{~kg}$ ?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:33

Problem 32

If Avogadro's number of pennies is divided equally among the 300 million men, women, and children in the United States, how many dollars would each receive? How does this compare with the gross domestic product (GDP) of the United States, which was $\$ 14.4$ trillion in $2008 ?$ (The GDP is the total market value of the nation's goods and services.)

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:11

Problem 33

Calculate the following quantities:
(a) mass, in grams, of 0.105 mole of sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$
(b) moles of $\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}$ in $143.50 \mathrm{~g}$ of this substance
(c) number of molecules in $1.0 \times 10^{-6} \mathrm{~mol} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$
(d) number of $\mathrm{N}$ atoms in $0.410 \mathrm{~mol} \mathrm{NH}_{3}$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:35

Problem 34

Calculate the following quantities:
(a) mass, in grams, of $1.50 \times 10^{-2} \mathrm{~mol}$ of CdS
(b) number of moles of $\mathrm{NH}_{4} \mathrm{Cl}$ in $86.6 \mathrm{~g}$ of this substance
(c) number of molecules in $8.447 \times 10^{-2} \mathrm{~mol} \mathrm{C}_{6} \mathrm{H}_{6}$
(d) number of $\mathrm{O}$ atoms in $6.25 \times 10^{-3} \mathrm{~mol} \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
03:44

Problem 35

(a) What is the mass, in grams, of $2.50 \times 10^{-3} \mathrm{~mol}$ of ammonium phosphate?
(b) How many moles of chloride ions are in $0.2550 \mathrm{~g}$ of aluminum chloride?
(c) What is the mass, in grams, of $7.70 \times 10^{20}$ molecules of caffeine, $\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2} ?$
(d) What is the molar mass of cholesterol if $0.00105 \mathrm{~mol}$ has a mass of $0.406 \mathrm{~g} ?$

Aadit Sharma
Aadit Sharma
Numerade Educator
08:59

Problem 36

(a) What is the mass, in grams, of $1.223 \mathrm{~mol}$ of iron(III) sulfate?
(b) How many moles of ammonium ions are in $6.955 \mathrm{~g}$ of ammonium carbonate?
(c) What is the mass, in grams, of $1.50 \times 10^{21}$ molecules of aspirin, $\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4} ?$
(d) What is the molar mass of diazepam (Valium $^{\circ}$ ) if 0.05570 mol has a mass of $15.86 \mathrm{~g}$ ?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:52

Problem 37

The molecular formula of allicin, the compound responsible for the characteristic smell of garlic, is $\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{OS}_{2} .$ (a) What is the molar mass of allicin? (b) How many moles of allicin are present in $5.00 \mathrm{mg}$ of this substance? $(\mathrm{c})$ How many molecules of allicin are in $5.00 \mathrm{mg}$ of this substance? (d) How many S atoms are present in $5.00 \mathrm{mg}$ of allicin?

Aadit Sharma
Aadit Sharma
Numerade Educator
06:58

Problem 38

The molecular formula of aspartame, the artificial sweetener marketed as NutraSweet $^{\oplus}$, is $\mathrm{C}_{14} \mathrm{H}_{18} \mathrm{~N}_{2} \mathrm{O}_{5} .$ (a) What is the molar mass of aspartame? (b) How many moles of aspartame are present in $1.00 \mathrm{mg}$ of aspartame? (c) How many molecules of aspartame are present in $1.00 \mathrm{mg}$ of aspartame?
(d) How many hydrogen atoms are present in $1.00 \mathrm{mg}$ of aspartame?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:22

Problem 39

A sample of glucose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6},$ contains $1.250 \times 10^{21}$ carbon atoms. (a) How many atoms of hydrogen does it contain?
(b) How many molecules of glucose does it contain?
(c) How many moles of glucose does it contain?
(d) What is the mass of this sample in grams?

Aadit Sharma
Aadit Sharma
Numerade Educator
10:08

Problem 40

A sample of the male sex hormone testosterone, $\mathrm{C}_{19} \mathrm{H}_{28} \mathrm{O}_{2}$, contains $3.88 \times 10^{21}$ hydrogen atoms. (a) How many atoms of carbon does it contain? (b) How many molecules of testosterone does it contain? (c) How many moles of testosterone does it contain? (d) What is the mass of this sample in grams?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
01:41

Problem 41

The allowable concentration level of vinyl chloride, $\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{Cl},$ in the atmosphere in a chemical plant is $2.0 \times 10^{-6} \mathrm{~g} / \mathrm{L}$. How many moles of vinyl chloride in each liter does this represent? How many molecules per liter?

Aadit Sharma
Aadit Sharma
Numerade Educator
05:38

Problem 42

At least $25 \mu \mathrm{g}$ of tetrahydrocannabinol (THC), the active ingredient in marijuana, is required to produce intoxication. The molecular formula of THC is $\mathrm{C}_{21} \mathrm{H}_{30} \mathrm{O}_{2}$. How many moles of THC does this $25 \mu \mathrm{g}$ represent? How many molecules?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
04:18

Problem 42

At least $25 \mu \mathrm{g}$ of tetrahydrocannabinol $(\mathrm{THC}),$ the active ingredient in marijuana, is required to produce intoxication. The molecular formula of $\mathrm{THC}$ is $\mathrm{C}_{21} \mathrm{H}_{30} \mathrm{O}_{2}$. How many moles of THC does this 25 \mug represent? How many molecules?
(b) Caffeine, a stimulant found in coffee, contains $49.5 \% \mathrm{C}$, $5.15 \% \mathrm{H}, 28.9 \% \mathrm{~N},$ and $16.5 \% \mathrm{O}$ by mass and has a molar mass of $195 \mathrm{~g} / \mathrm{mol}$.
(c) Monosodium glutamate (MSG), a flavor enhancer in certain foods, contains $35.51 \% \mathrm{C}, 4.77 \% \mathrm{H}, 37.85 \% \mathrm{O},$
$8.29 \% \mathrm{~N},$ and $13.60 \% \mathrm{Na},$ and has a molar mass of $169 \mathrm{~g} / \mathrm{mol}$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:56

Problem 43

Give the empirical formula of each of the following compounds if a sample contains
(a) $0.0130 \mathrm{~mol} \mathrm{C}, 0.0390 \mathrm{~mol} \mathrm{H},$
and $0.0065 \mathrm{~mol} \mathrm{O} ;$ (b) $11.66 \mathrm{~g}$ iron and $5.01 \mathrm{~g}$ oxygen; (c)
$40.0 \% \mathrm{C}, 6.7 \% \mathrm{H},$ and $53.3 \% \mathrm{O}$ by mass.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
10:50

Problem 44

Determine the empirical formula of each of the following compounds if a sample contains
(a) $0.104 \mathrm{~mol} \mathrm{~K}, 0.052 \mathrm{~mol} \mathrm{C}$,
and $0.156 \mathrm{~mol} \mathrm{O} ;$ (b) $5.28 \mathrm{~g} \mathrm{Sn}$ and $3.37 \mathrm{~g} \mathrm{~F}$;
(c) $87.5 \% \mathrm{~N}$ and
$12.5 \% \mathrm{H}$ by mass.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:37

Problem 45

Determine the empirical formulas of the compounds with the following compositions by mass:
(a) $10.4 \% \mathrm{C}, 27.8 \% \mathrm{~S},$ and $61.7 \% \mathrm{Cl}$
(b) $21.7 \% \mathrm{C}, 9.6 \% \mathrm{O},$ and $68.7 \% \mathrm{~F}$
(c) $32.79 \% \mathrm{Na}, 13.02 \% \mathrm{Al},$ and the remainder $\mathrm{F}$

Aadit Sharma
Aadit Sharma
Numerade Educator
15:04

Problem 46

Determine the empirical formulas of the compounds with the following compositions by mass:
(a) $55.3 \% \mathrm{~K}, 14.6 \% \mathrm{P}$, and $30.1 \% \mathrm{O}$
(b) $24.5 \% \mathrm{Na}, 14.9 \% \mathrm{Si},$ and $60.6 \% \mathrm{~F}$
(c) $62.1 \% \mathrm{C}, 5.21 \% \mathrm{H}, 12.1 \% \mathrm{~N},$ and the remainder $\mathrm{O}$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
03:26

Problem 47

A compound whose empirical formula is $\mathrm{XF}_{3}$ consists of $65 \%$ F by mass. What is the atomic mass of X?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
06:11

Problem 48

The compound $\mathrm{XCl}_{4}$ contains $75.0 \% \mathrm{Cl}$ by mass. What is the element $\mathrm{X} ?$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
01:29

Problem 49

What is the molecular formula of each of the following compounds?
(a) empirical formula $\mathrm{CH}_{2}$, molar mass $=84 \mathrm{~g} / \mathrm{mol}$
(b) empirical formula $\mathrm{NH}_{2} \mathrm{Cl}$, molar mass $=51.5 \mathrm{~g} / \mathrm{mol}$

Aadit Sharma
Aadit Sharma
Numerade Educator
06:22

Problem 50

What is the molecular formula of each of the following compounds?
(a) empirical formula $\mathrm{HCO}_{2},$ molar mass $=90.0 \mathrm{~g} / \mathrm{mol}$
(b) empirical formula $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O},$ molar mass $=88 \mathrm{~g} / \mathrm{mol}$.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
09:42

Problem 51

Determine the empirical and molecular formulas of each of the following substances:
(a) Styrene, a compound substance used to make Styrofoam $^{\circledast}$ cups and insulation, contains $92.3 \% \mathrm{C}$ and $7.7 \% \mathrm{H}$ by mass and has a molar mass of $104 \mathrm{~g} / \mathrm{mol}$ (b) Caffeine, a stimulant found in coffee, contains $49.5 \% \mathrm{C}$, $5.15 \% \mathrm{H}, 28.9 \% \mathrm{~N},$ and $16.5 \% \mathrm{O}$ by mass and has a molar mass of $195 \mathrm{~g} / \mathrm{mol}$ (c) Monosodium glutamate (MSG), a flavor enhancer in certain foods, contains $35.51 \%$ C, $4.77 \%$ H, $37.85 \%$ O, $8.29 \% \mathrm{~N},$ and $13.60 \% \mathrm{Na},$ and has a molar mass of $169 \mathrm{~g} / \mathrm{mol}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
10:33

Problem 52

Determine the empirical and molecular formulas of each of the following substances:
(a) Ibuprofen, a headache remedy, contains $75.69 \% \mathrm{C}, 8.80 \%$ $\mathrm{H},$ and $15.51 \% \mathrm{O}$ by mass, and has a molar mass of $206 \mathrm{~g} / \mathrm{mol}$
(b) Cadaverine, a foul-smelling substance produced by the action of bacteria on meat, contains $58.55 \% \mathrm{C}, 13.81 \% \mathrm{H},$ and $27.40 \% \mathrm{~N}$ by mass; its molar mass is $102.2 \mathrm{~g} / \mathrm{mol}$.
(c) Epinephrine (adrenaline), a hormone secreted into the bloodstream in times of danger or stress, contains $59.0 \% \mathrm{C}$, $7.1 \% \mathrm{H}, 26.2 \% \mathrm{O},$ and $7.7 \% \mathrm{~N}$ by mass; its $\mathrm{MW}$ is about 180 amu.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
12:31

Problem 53

(a) Combustion analysis of toluene, a common organic solvent, gives $5.86 \mathrm{mg}$ of $\mathrm{CO}_{2}$ and $1.37 \mathrm{mg}$ of $\mathrm{H}_{2} \mathrm{O}$. If the compound contains only carbon and hydrogen, what is its empirical formula? (b) Menthol, the substance we can smell in mentholated cough drops, is composed of $\mathrm{C}, \mathrm{H},$ and $\mathrm{O} . \mathrm{A}$ 0.1005-g sample of menthol is combusted, producing $0.2829 \mathrm{~g}$ of $\mathrm{CO}_{2}$ and $0.1159 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$. What is the empirical formula for menthol? If menthol has a molar mass of $156 \mathrm{~g} / \mathrm{mol}$, what is its molecular formula?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
15:04

Problem 54

(a) The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of $2.78 \mathrm{mg}$ of ethyl butyrate produces $6.32 \mathrm{mg}$ of $\mathrm{CO}_{2}$ and $2.58 \mathrm{mg}$ of $\mathrm{H}_{2} \mathrm{O}$. What is the empirical formula of the compound? (b) Nicotine, a component of tobacco, is composed of $\mathrm{C}, \mathrm{H},$ and $\mathrm{N}$. A 5.250 -mg sample of nicotine was combusted, producing $14.242 \mathrm{mg}$ of $\mathrm{CO}_{2}$ and $4.083 \mathrm{mg}$ of $\mathrm{H}_{2} \mathrm{O}$. What is the empirical formula for nicotine? If nicotine has a molar mass of $160 \pm 5 \mathrm{~g} / \mathrm{mol}$, what is its molecular formula?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
05:44

Problem 55

Valproic acid, used to treat seizures and bipolar disorder, is composed of $\mathrm{C}, \mathrm{H},$ and $\mathrm{O} .$ A $0.165-\mathrm{g}$ sample is combusted in an apparatus such as that shown in Figure $3.14 .$ The gain in mass of the $\mathrm{H}_{2} \mathrm{O}$ absorber is $0.166 \mathrm{~g}$, whereas that of the $\mathrm{CO}_{2}$ absorber is $0.403 \mathrm{~g}$. What empirical formula for valproic acid do these results indicate? Is this empirical formula consistent with the molecular model shown here?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:54

Problem 56

Propenoic acid, as shown here,

Henry He
Henry He
Numerade Educator
06:52

Problem 56

Propenoic acid, as shown here, is a reactive organic liquid used in the manufacture of plastics, coatings, and adhesives. An unlabeled container is thought to contain this acid. A 0.2033 -g sample is combusted in an apparatus such as that shown in Figure $3.14 .$ The gain in mass of the $\mathrm{H}_{2} \mathrm{O}$ absorber is $0.102 \mathrm{~g},$ whereas that of the $\mathrm{CO}_{2}$ absorber is $0.374 \mathrm{~g}$. Is this analysis consistent with the contents of the container being propenoic acid?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:13

Problem 57

Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure.
Its formula can be written as $\mathrm{Na}_{2} \mathrm{CO}_{3} \cdot x \mathrm{H}_{2} \mathrm{O},$ where $x$ is the number of moles of $\mathrm{H}_{2} \mathrm{O}$ per mole of $\mathrm{Na}_{2} \mathrm{CO}_{3}$. When a $2.558-\mathrm{g}$ sample of washing soda is heated at $25^{\circ} \mathrm{C},$ all the water of hydration is lost, leaving $0.948 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3} .$ What is the value of $x ?$

Narayan Hari
Narayan Hari
Numerade Educator
07:22

Problem 58

Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as $\mathrm{MgSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O},$ where $x$ indicates the number of moles of $\mathrm{H}_{2} \mathrm{O}$ per mole of $\mathrm{MgSO}_{4}$. When $5.061 \mathrm{~g}$ of this hydrate is heated to $250{ }^{\circ} \mathrm{C},$ all the water of hydration is lost, leaving $2.472 \mathrm{~g}$ of $\mathrm{MgSO}_{4}$. What is the value of $x ?$

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:04

Problem 59

Why is it essential to use balanced chemical equations when determining the quantity of a product formed from a given quantity of a reactant?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:11

Problem 60

What parts of balanced chemical equations give information about the relative numbers of moles of reactants and products involved in a reaction?

Narayan Hari
Narayan Hari
Numerade Educator
06:32

Problem 61

Hydrofluoric acid, $\mathrm{HF}(a q),$ cannot be stored in glass bottles because compounds called silicates in the glass are attacked by the $\mathrm{HF}(a q)$. Sodium silicate $\left(\mathrm{Na}_{2} \mathrm{SiO}_{3}\right)$, for example, reacts as follows:
$$
\begin{aligned}
\mathrm{Na}_{2} \mathrm{SiO}_{3}(s)+8 \mathrm{HF}(a q) & \longrightarrow \\
\mathrm{H}_{2} \mathrm{SiF}_{6}(a q) &+2 \mathrm{NaF}(a q)+3 \mathrm{H}_{2} \mathrm{O}(l)
\end{aligned}
$$
(a) How many moles of HF are needed to react with 0.300 $\mathrm{mol}$ of $\mathrm{Na}_{2} \mathrm{SiO}_{3} ?$
(b) How many grams of NaF form when $0.500 \mathrm{~mol}$ of HF reacts with excess $\mathrm{Na}_{2} \mathrm{SiO}_{3} ?$
(c) How many grams of $\mathrm{Na}_{2} \mathrm{SiO}_{3}$ can react with $0.800 \mathrm{~g}$ of HF?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:37

Problem 62

The reaction between potassium superoxide, $\mathrm{KO}_{2}$, and $\mathrm{CO}_{2}$,
$$
4 \mathrm{KO}_{2}+2 \mathrm{CO}_{2} \longrightarrow 2 \mathrm{~K}_{2} \mathrm{CO}_{3}+3 \mathrm{O}_{2}
$$
is used as a source of $\mathrm{O}_{2}$ and absorber of $\mathrm{CO}_{2}$ in self-contained breathing equipment used by rescue workers.
(a) How many moles of $\mathrm{O}_{2}$ are produced when $0.400 \mathrm{~mol}$ of $\mathrm{KO}_{2}$ reacts in this fashion?
(b) How many grams of $\mathrm{KO}_{2}$ are needed to form $7.50 \mathrm{~g}$ of $\mathrm{O}_{2}$ ?
(c) How many grams of $\mathrm{CO}_{2}$ are used when $7.50 \mathrm{~g}$ of $\mathrm{O}_{2}$ are produced?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
09:02

Problem 63

Several brands of antacids use $\mathrm{Al}(\mathrm{OH})_{3}$ to react with stomach acid, which contains primarily $\mathrm{HCl}$ :
$\mathrm{Al}(\mathrm{OH})_{3}(s)+\mathrm{HCl}(a q) \longrightarrow \mathrm{AlCl}_{3}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$
(a) Balance this equation.
(b) Calculate the number of grams of $\mathrm{HCl}$ that can react with $0.500 \mathrm{~g}$ of $\mathrm{Al}(\mathrm{OH})_{3}$
(c) Calculate the number of grams of $\mathrm{AlCl}_{3}$ and the number of grams of $\mathrm{H}_{2} \mathrm{O}$ formed when $0.500 \mathrm{~g}$ of $\mathrm{Al}(\mathrm{OH})_{3}$ reacts.
(d) Show that your calculations in parts (b) and (c) are consistent with the law of conservation of mass.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
12:25

Problem 64

An iron ore sample contains $\mathrm{Fe}_{2} \mathrm{O}_{3}$ together with other substances. Reaction of the ore with CO produces iron metal:
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+\mathrm{CO}(g) \longrightarrow \mathrm{Fe}(s)+\mathrm{CO}_{2}(g)
$$
(a) Balance this equation.
(b) Calculate the number of grams of CO that can react with
$$
0.350 \mathrm{~kg} \text { of } \mathrm{Fe}_{2} \mathrm{O}_{3}
$$
(c) Calculate the number of grams of Fe and the number of grams of $\mathrm{CO}_{2}$ formed when $0.350 \mathrm{~kg}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ reacts.
(d) Show that your calculations in parts (b) and (c) are consistent with the law of conservation of mass.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:30

Problem 65

Aluminum sulfide reacts with water to form aluminum hydroxide and hydrogen sulfide. (a) Write the balanced chemical equation for this reaction. (b) How many grams of aluminum hydroxide are obtained from $14.2 \mathrm{~g}$ of aluminum sulfide?

Aadit Sharma
Aadit Sharma
Numerade Educator
07:07

Problem 66

Calcium hydride reacts with water to form calcium hydroxide and hydrogen gas. (a) Write a balanced chemical equation for the reaction. (b) How many grams of calcium hydride are needed to form $4.500 \mathrm{~g}$ of hydrogen?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
04:45

Problem 67

Automotive air bags inflate when sodium azide, $\mathrm{NaN}_{3}$, rapidly decomposes to its component elements:
$$
2 \mathrm{NaN}_{3}(s) \longrightarrow 2 \mathrm{Na}(s)+3 \mathrm{~N}_{2}(g)
$$
(a) How many moles of $\mathrm{N}_{2}$ are produced by the decomposition of $1.50 \mathrm{~mol}$ of $\mathrm{NaN}_{3} ?$
(b) How many grams of $\mathrm{NaN}_{3}$ are required to form $10.0 \mathrm{~g}$ of nitrogen gas?
(c) How many grams of $\mathrm{NaN}_{3}$ are required to produce $10.0 \mathrm{ft}^{3}$ of nitrogen gas, about the size of an automotive air bag, if the gas has a density of $1.25 \mathrm{~g} / \mathrm{L}$ ?

Aadit Sharma
Aadit Sharma
Numerade Educator
07:55

Problem 68

The complete combustion of octane, $\mathrm{C}_{8} \mathrm{H}_{18}$, the main component of gasoline, proceeds as follows:
$2 \mathrm{C}_{8} \mathrm{H}_{18}(l)+25 \mathrm{O}_{2}(g) \longrightarrow 16 \mathrm{CO}_{2}(g)+18 \mathrm{H}_{2} \mathrm{O}(g)$
(a) How many moles of $\mathrm{O}_{2}$ are needed to burn $1.50 \mathrm{~mol}$ of $\mathrm{C}_{8} \mathrm{H}_{18} ?$
(b) How many grams of $\mathrm{O}_{2}$ are needed to burn $10.0 \mathrm{~g}$ of $\mathrm{C}_{8} \mathrm{H}_{18} ?$
(c) Octane has a density of $0.692 \mathrm{~g} / \mathrm{mL}$ at $20^{\circ} \mathrm{C}$. How many grams of $\mathrm{O}_{2}$ are required to burn $15.0 \mathrm{gal}$ of $\mathrm{C}_{8} \mathrm{H}_{18}$ (the capacity of an average fuel tank)?
(d) How many grams of $\mathrm{CO}_{2}$ are produced when 15.0 gal of $\mathrm{C}_{8} \mathrm{H}_{18}$ are combusted?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:17

Problem 69

A piece of aluminum foil $1.00 \mathrm{~cm}$ square and $0.550 \mathrm{~mm}$ thick is allowed to react with bromine to form aluminum bromide.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:09

Problem 69

A piece of aluminum foil $1.00 \mathrm{~cm}$ square and $0.550 \mathrm{~mm}$ thick is allowed to react with bromine to form aluminum bromide.
(a) How many moles of aluminum were used? (The density of aluminum is $\left.2.699 \mathrm{~g} / \mathrm{cm}^{3} .\right)$ (b) How many grams of aluminum bromide form, assuming the aluminum reacts completelv?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:46

Problem 70

Detonation of nitroglycerin proceeds as follows:
$4 \mathrm{C}_{3} \mathrm{H}_{5} \mathrm{~N}_{3} \mathrm{O}_{9}(l) \longrightarrow$
$$
12 \mathrm{CO}_{2}(g)+6 \mathrm{~N}_{2}(g)+\mathrm{O}_{2}(g)+10 \mathrm{H}_{2} \mathrm{O}(g)
$$
(a) If a sample containing $2.00 \mathrm{~mL}$ of nitroglycerin (density $=$ $1.592 \mathrm{~g} / \mathrm{mL}$ ) is detonated, how many total moles of gas are produced? (b) If each mole of gas occupies $55 \mathrm{~L}$ under the conditions of the explosion, how many liters of gas are produced? (c) How many grams of $\mathrm{N}_{2}$ are produced in the detonation?
can be filled and capped? (b) How much of each item is left over? (c) Which component limits the production?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:22

Problem 71

(a) Define the terms limiting reactant and excess reactant. (b) Why are the amounts of products formed in a reaction determined only by the amount of the limiting reactant? (c) Why should you base your choice of which compound is the limiting reactant on its number of initial moles, not on its initial mass in grams?

Aadit Sharma
Aadit Sharma
Numerade Educator
04:09

Problem 72

(a) Define the terms theoretical yield, actual yield, and percent yield. (b) Why is the actual yield in a reaction almost always less than the theoretical yield?
(c) Can a reaction ever have $110 \%$ actual yield?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:25

Problem 73

A manufacturer of bicycles has 4815 wheels, 2305 frames, and 2255 handlebars. (a) How many bicycles can be manufactured using these parts? (b) How many parts of each kind are left over? (c) Which part limits the production of bicycles?

Narayan Hari
Narayan Hari
Numerade Educator
05:50

Problem 74

A bottling plant has 126,515 bottles with a capacity of $355 \mathrm{~mL}$, 108,500 caps, and $48,775 \mathrm{~L}$ of beverage.
(a) How many bottles can be filled and capped?
(b) How much of each item is left over? (c) Which component limits the production?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
05:14

Problem 75

Sodium hydroxide reacts with carbon dioxide as follows:
$2 \mathrm{NaOH}(s)+\mathrm{CO}_{2}(g) \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(l)$
Which is the limiting reactant when $1.85 \mathrm{~mol} \mathrm{NaOH}$ and 1.00 $\mathrm{mol} \mathrm{CO}_{2}$ are allowed to react? How many moles of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ can be produced? How many moles of the excess reactant remain after the completion of the reaction?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
05:59

Problem 76

Aluminum hydroxide reacts with sulfuric acid as follows:
$$
2 \mathrm{Al}(\mathrm{OH})_{3}(s)+3 \mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l)
$$
Which is the limiting reactant when $0.500 \mathrm{~mol} \mathrm{Al}(\mathrm{OH})_{3}$ and $0.500 \mathrm{~mol} \mathrm{H}_{2} \mathrm{SO}_{4}$ are allowed to react? How many moles of $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ can form under these conditions? How many moles of the excess reactant remain after the completion of the reaction?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
07:51

Problem 77

The fizz produced when an Alka-Seltzer $^{\circledast}$ tablet is dissolved in water is due to the reaction between sodium bicarbonate $\left(\mathrm{NaHCO}_{3}\right)$ and citric acid $\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right)$
$$
\begin{aligned}
3 \mathrm{NaHCO}_{3}(a q)+\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(a q) \longrightarrow \\
& 3 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(a q)
\end{aligned}
$$
In a certain experiment $1.00 \mathrm{~g}$ of sodium bicarbonate and $1.00 \mathrm{~g}$ of citric acid are allowed to react.
(a) Which is the limiting reactant?
(b) How many grams of carbon dioxide form?
(c) How many grams of the excess reactant remain after the limiting reactant is completely consumed?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
13:00

Problem 78

One of the steps in the commercial process for converting ammonia to nitric acid is the conversion of $\mathrm{NH}_{3}$ to NO:
$4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$
In a certain experiment, $2.00 \mathrm{~g}$ of $\mathrm{NH}_{3}$ reacts with $2.50 \mathrm{~g}$ of $\mathrm{O}_{2}$
(a) Which is the limiting reactant? (b) How many grams of $\mathrm{NO}$ and of $\mathrm{H}_{2} \mathrm{O}$ form? (c) How many grams of the excess reactant remain after the limiting reactant is completely consumed? (d) Show that your calculations in parts (b) and
(c) are consistent with the law of conservation of mass.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
03:01

Problem 79

Solutions of sodium carbonate and silver nitrate react to form solid silver carbonate and a solution of sodium nitrate. A solution containing $3.50 \mathrm{~g}$ of sodium carbonate is mixed with one containing $5.00 \mathrm{~g}$ of silver nitrate. How many grams of sodium carbonate, silver nitrate, silver carbonate, and sodium nitrate are present after the reaction is complete?

Aadit Sharma
Aadit Sharma
Numerade Educator
09:21

Problem 80

Solutions of sulfuric acid and lead(II) acetate react to form solid lead(II) sulfate and a solution of acetic acid. If $5.00 \mathrm{~g}$ of sulfuric acid and $5.00 \mathrm{~g}$ of lead(II) acetate are mixed, calculate the number of grams of sulfuric acid, lead(II) acetate, lead(II) sulfate, and acetic acid present in the mixture after the reaction is complete.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
05:16

Problem 81

When benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ reacts with bromine $\left(\mathrm{Br}_{2}\right)$, bromobenzene $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}\right)$ is obtained:
$$
\mathrm{C}_{6} \mathrm{H}_{6}+\mathrm{Br}_{2} \longrightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}+\mathrm{HBr}
$$
(a) When $30.0 \mathrm{~g}$ of benzene reacts with $65.0 \mathrm{~g}$ of bromine, what is the theoretical yield of bromobenzene? (b) If the actual yield of bromobenzene is $42.3 \mathrm{~g}$, what is the percentage yield?

Aadit Sharma
Aadit Sharma
Numerade Educator
09:04

Problem 82

When ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$ reacts with chlorine $\left(\mathrm{Cl}_{2}\right)$, the main product is $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}$, but other products containing $\mathrm{Cl}$, such as $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2},$ are also obtained in small quantities. The formation of these other products reduces the yield of $\mathrm{C}_{2} \mathrm{H}_{5}$ Cl. (a) Calculate the theoretical yield of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}$ when $125 \mathrm{~g}$ of $\mathrm{C}_{2} \mathrm{H}_{6}$ reacts with $255 \mathrm{~g}$ of $\mathrm{Cl}_{2}$, assuming that $\mathrm{C}_{2} \mathrm{H}_{6}$ and $\mathrm{Cl}_{2}$ react only to form $\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{Cl}$ and HCl. (b) Calculate the percent yield of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}$ if the reaction produces $206 \mathrm{~g}$ of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:02

Problem 83

Hydrogen sulfide is an impurity in natural gas that must be removed. One common removal method is called the Claus process, which relies on the reaction:
$$
8 \mathrm{H}_{2} \mathrm{~S}(g)+4 \mathrm{O}_{2}(g) \longrightarrow \mathrm{S}_{8}(l)+8 \mathrm{H}_{2} \mathrm{O}(g)
$$
Under optimal conditions the Claus process gives $98 \%$ yield of $\mathrm{S}_{8}$ from $\mathrm{H}_{2} \mathrm{~S}$. If you started with 30.0 grams of $\mathrm{H}_{2} \mathrm{~S}$ and 50.0 grams of $\mathrm{O}_{2}$, how many grams of $\mathrm{S}_{8}$ would be produced, assuming $98 \%$ yield?

Aadit Sharma
Aadit Sharma
Numerade Educator
05:52

Problem 84

When hydrogen sulfide gas is bubbled into a solution of sodium hydroxide, the reaction forms sodium sulfide and water. How many grams of sodium sulfide are formed if $1.25 \mathrm{~g}$ of hydrogen sulfide is bubbled into a solution containing $2.00 \mathrm{~g}$ of sodium hydroxide, assuming that the sodium sulfide is made in $92.0 \%$ yield?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
03:37

Problem 85

Write the balanced chemical equations for (a) the complete combustion of acetic acid $\left(\mathrm{CH}_{3} \mathrm{COOH}\right)$, the main active ingredient in vinegar; $(\mathbf{b})$ the decomposition of solid calcium hydroxide into solid calcium(II) oxide (lime) and water vapor; (c) the combination reaction between nickel metal and chlorine gas.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
05:30

Problem 86

If $1.5 \mathrm{~mol} \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, 1.5 \mathrm{~mol} \mathrm{C}_{3} \mathrm{H}_{8},$ and $1.5 \mathrm{~mol} \mathrm{CH}_{3} \mathrm{CH}_{2}$
$\mathrm{COCH}_{3}$ are completely combusted in oxygen, which produces the largest number of moles of $\mathrm{H}_{2} \mathrm{O} ?$ Which produces the least? Explain.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:40

Problem 87

The effectiveness of nitrogen fertilizers depends on both their ability to deliver nitrogen to plants and the amount of nitrogen they can deliver. Four common nitrogen-containing fertilizers are ammonia, ammonium nitrate, ammonium sulfate, and urea $\left[\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}\right]$. Rank these fertilizers in terms of the mass percentage nitrogen they contain.

Aadit Sharma
Aadit Sharma
Numerade Educator
05:22

Problem 88

(a) The molecular formula of acetylsalicylic acid (aspirin), one of the most common pain relievers, is $\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}$. How many moles of $\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}$ are in a 0.500 -g tablet of aspirin?
(b) How many molecules of $\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}$ are in this tablet?
(c) How many carbon atoms are in the tablet?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
09:27

Problem 89

Very small crystals composed of 1000 to 100,000 atoms, called quantum dots, are being investigated for use in electronic devices.
(a) A quantum dot was made of solid silicon in the shape of a sphere, with a diameter of $4 \mathrm{nm} .$ Calculate the mass of the quantum dot, using the density of silicon $\left(2.3 \mathrm{~g} / \mathrm{cm}^{3}\right)$
(b) How many silicon atoms are in the quantum dot?
(c) The density of germanium is $5.325 \mathrm{~g} / \mathrm{cm}^{3}$. If you made a 4-nm quantum dot of germanium, how many Ge atoms would it contain? Assume the dot is spherical.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:17

Problem 90

(a) One molecule of the antibiotic penicillin G has a mass of $5.342 \times 10^{-21} \mathrm{~g} .$ What is the molar mass of penicillin G?
(b) Hemoglobin, the oxygen-carrying protein in red blood cells, has four iron atoms per molecule and contains $0.340 \%$ iron by mass. Calculate the molar mass of hemoglobin.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
07:39

Problem 91

Serotonin is a compound that conducts nerve impulses in the brain. It contains 68.2 mass percent C, 6.86 mass percent $\mathrm{H}$, 15.9 mass percent $\mathrm{N},$ and 9.08 mass percent $\mathrm{O}$. Its molar mass is $176 \mathrm{~g} / \mathrm{mol}$. Determine its molecular formula.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
08:10

Problem 92

The koala dines exclusively on eucalyptus leaves. Its digestive system detoxifies the eucalyptus oil, a poison to other animals. The chief constituent in eucalyptus oil is a substance called eucalyptol, which contains $77.87 \% \mathrm{C}, 11.76 \% \mathrm{H},$ and the remainder O. (a) What is the empirical formula for this substance? (b) A mass spectrum of eucalyptol shows a peak at about 154 amu. What is the molecular formula of the substance?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
02:42

Problem 93

Vanillin, the dominant flavoring in vanilla, contains C, H, and
O. When $1.05 \mathrm{~g}$ of this substance is completely combusted, $2.43 \mathrm{~g}$ of $\mathrm{CO}_{2}$ and $0.50 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$ are produced. What is the empirical formula of vanillin?

Aadit Sharma
Aadit Sharma
Numerade Educator
10:49

Problem 94

An organic compound was found to contain only $\mathrm{C}, \mathrm{H},$ and Cl. When a 1.50 -g sample of the compound was completely combusted in air, $3.52 \mathrm{~g}$ of $\mathrm{CO}_{2}$ was formed. In a separate experiment the chlorine in a 1.00 -g sample of the compound was converted to $1.27 \mathrm{~g}$ of AgCl. Determine the empirical formula of the compound.

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
03:25

Problem 95

A compound, $\mathrm{KBrO}_{x}$, where $x$ is unknown, is analyzed and found to contain $52.92 \%$ Br. What is the value of $x ?$

Aadit Sharma
Aadit Sharma
Numerade Educator
06:32

Problem 96

An element $X$ forms an iodide $\left(\mathrm{Xl}_{3}\right)$ and a chloride $\left(\mathrm{XCl}_{3}\right)$. The iodide is quantitatively converted to the chloride when it is heated in a stream of chlorine:
$$
2 \mathrm{XI}_{3}+3 \mathrm{Cl}_{2} \longrightarrow 2 \mathrm{XCl}_{3}+3 \mathrm{I}_{2}
$$
If $0.5000 \mathrm{~g}$ of $\mathrm{Xl}_{3}$ is treated, $0.2360 \mathrm{~g}$ of $\mathrm{XCl}_{3}$ is obtained. (a) Calculate the atomic weight of the element X. (b) Identify the element X.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:11

Problem 97

A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a "bubbler" containing sodium iodide, which removes the ozone according to the following equation:
$\mathrm{O}_{3}(g)+2 \mathrm{NaI}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow$
$$
\mathrm{O}_{2}(g)+\mathrm{I}_{2}(s)+2 \mathrm{NaOH}(a q)
$$
(a) How many moles of sodium iodide are needed to remove $5.95 \times 10^{-6} \mathrm{~mol}$ of $\mathrm{O}_{3} ?$ (b) How many grams of sodium iodide are needed to remove $1.3 \mathrm{mg}$ of $\mathrm{O}_{3} ?$

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
04:23

Problem 98

A chemical plant uses electrical energy to decompose aqueous solutions of $\mathrm{NaCl}$ to give $\mathrm{Cl}_{2}, \mathrm{H}_{2}$, and $\mathrm{NaOH}$ :
$$
\begin{aligned}
\mathrm{NaCl}(a q)+2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow & \\
& 2 \mathrm{NaOH}(a q)+\mathrm{H}_{2}(g)+\mathrm{Cl}_{2}(g)
\end{aligned}
$$
If the plant produces $1.5 \times 10^{6} \mathrm{~kg}(1500$ metric tons $)$ of $\mathrm{Cl}_{2}$ daily, estimate the quantities of $\mathrm{H}_{2}$ and $\mathrm{NaOH}$ produced.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:43

Problem 99

The fat stored in a camel's hump is a source of both energy and water. Calculate the mass of $\mathrm{H}_{2} \mathrm{O}$ produced by metabolism of 1.0 $\mathrm{kg}$ of fat, assuming the fat consists entirely of tristearin $\left(\mathrm{C}_{57} \mathrm{H}_{110} \mathrm{O}_{6}\right)$, a typical animal fat, and assuming that during metabolism, tristearin reacts with $\mathrm{O}_{2}$ to form only $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
16:55

Problem 100

When hydrocarbons are burned in a limited amount of air, both $\mathrm{CO}$ and $\mathrm{CO}_{2}$ form. When $0.450 \mathrm{~g}$ of a particular hydrocarbon was burned in air, $0.467 \mathrm{~g}$ of $\mathrm{CO}, 0.733 \mathrm{~g}$ of $\mathrm{CO}_{2},$ and $0.450 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$ were formed.
(a) What is the empirical formula of the compound? (b) How many grams of $\mathrm{O}_{2}$ were used in the reaction? (c) How many grams would have been required for complete combustion?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
04:44

Problem 101

A mixture of $\mathrm{N}_{2}(g)$ and $\mathrm{H}_{2}(g)$ reacts in a closed container to form ammonia, $\mathrm{NH}_{3}(g)$. The reaction ceases before either reactant has been totally consumed. At this stage $3.0 \mathrm{~mol} \mathrm{~N}_{2}, 3.0$ $\mathrm{mol} \mathrm{H}_{2},$ and $3.0 \mathrm{~mol} \mathrm{NH}_{3}$ are present. How many moles of $\mathrm{N}_{2}$ and $\mathrm{H}_{2}$ were present originally?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
15:01

Problem 102

A mixture containing $\mathrm{KClO}_{3}, \mathrm{~K}_{2} \mathrm{CO}_{3}, \mathrm{KHCO}_{3},$ and $\mathrm{KCl}$ was
heated, producing $\mathrm{CO}_{2}, \mathrm{O}_{2}$, and $\mathrm{H}_{2} \mathrm{O}$ gases according to the following equations:
$$
\begin{aligned}
2 \mathrm{KClO}_{3}(s) & \longrightarrow 2 \mathrm{KCl}(s)+3 \mathrm{O}_{2}(g) \\
2 \mathrm{KHCO}_{3}(s) & \longrightarrow \mathrm{K}_{2} \mathrm{O}(s)+\mathrm{H}_{2} \mathrm{O}(g)+2 \mathrm{CO}_{2}(g) \\
\mathrm{K}_{2} \mathrm{CO}_{3}(s) & \longrightarrow \mathrm{K}_{2} \mathrm{O}(s)+\mathrm{CO}_{2}(g)
\end{aligned}
$$
The KCl does not react under the conditions of the reaction. If $100.0 \mathrm{~g}$ of the mixture produces $1.80 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}, 13.20 \mathrm{~g}$ of $\mathrm{CO}_{2}$,
and $4.00 \mathrm{~g}$ of $\mathrm{O}_{2}$, what was the composition of the original mixture? (Assume complete decomposition of the mixture.)

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
09:40

Problem 103

When a mixture of $10.0 \mathrm{~g}$ of acetylene $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right) ;$ and $10.0 \mathrm{~g}$ of oxygen $\left(\mathrm{O}_{2}\right)$ is ignited, the resultant combustion reaction produces $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$
(a) Write the balanced chemical equation for this reaction. (b) Which is the limiting reactant?
(c) How many grams of $\mathrm{C}_{2} \mathrm{H}_{2}, \mathrm{O}_{2}, \mathrm{CO}_{2},$ and $\mathrm{H}_{2} \mathrm{O}$ are present after the
reaction is complete?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
14:41

Problem 104

Aspirin $\left(\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}\right)$ is produced from salicylic acid $\left(\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}\right)$
and acetic anhydride $\left(\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3}\right):$
$$
\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}+\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{3} \longrightarrow \mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}+\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}
$$
(a) How much salicylic acid is required to produce $1.5 \times 10^{2} \mathrm{~kg}$ of aspirin, assuming that all of the salicylic acid is converted to aspirin? (b) How much salicylic acid would be required if only $80 \%$ of the salicylic acid is converted to aspirin? (c) What is the theoretical yield of aspirin if $185 \mathrm{~kg}$ of salicylic acid is allowed to react with $125 \mathrm{~kg}$ of acetic anhydride? (d) If the situation described in part (c) produces $182 \mathrm{~kg}$ of aspirin, what is the percentage yield?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:50

Problem 105

Consider a sample of calcium carbonate in the form of a cube measuring 2.005 in. on each edge. If the sample has a density of $2.71 \mathrm{~g} / \mathrm{cm}^{3},$ how many oxygen atoms does it contain?

Md Mohibullah
Md Mohibullah
Auburn University Main Campus
07:22

Problem 106

(a) You are given a cube of silver metal that measures $1.000 \mathrm{~cm}$ on each edge. The density of silver is $10.5 \mathrm{~g} / \mathrm{cm}^{3}$. How many atoms are in this cube? (b) Because atoms are spherical, they cannot occupy all of the space of the cube. The silver atoms pack in the solid in such a way that $74 \%$ of the volume of the solid is actually filled with the silver atoms. Calculate the volume of a single silver atom. (c) Using the volume of a silver atom and the formula for the volume of a sphere, calculate the radius in angstroms of a silver atom.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:32

Problem 107

(a) If an automobile travels $225 \mathrm{mi}$ with a gas mileage of $20.5 \mathrm{mi} / \mathrm{gal}$, how many kilograms of $\mathrm{CO}_{2}$ are produced? Assume that the gasoline is composed of octane, $\mathrm{C}_{8} \mathrm{H}_{18}(l),$ whose density is $0.69 \mathrm{~g} / \mathrm{mL}$.
(b) Repeat the calculation for a truck that has a gas mileage of $5 \mathrm{mi} / \mathrm{gal}$.

Narayan Hari
Narayan Hari
Numerade Educator
03:37

Problem 108

Section 2.9 introduced the idea of structural isomerism, with 1-propanol and 2 -propanol as examples. Determine which of these properties would distinguish these two substances: (a) boiling point; (b) combustion analysis results; (c) molecular weight; (d) density at a given temperature and pressure. You can check on the properties of these two compounds in Wolfram Alpha (http://www.wolframalpha.com/) or the CRC Handbook of Chemistry and Physics.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:21

Problem 109

A particular coal contains $2.5 \%$ sulfur by mass. When this coal is burned at a power plant, the sulfur is converted into sulfur dioxide gas, which is a pollutant. To reduce sulfur dioxide emissions, calcium oxide (lime) is used. The sulfur dioxide reacts with calcium oxide to form solid calcium sulfite. (a) Write the balanced chemical equation for the reaction. (b) If the coal is burned in a power plant that uses 2000 tons of coal per day, what mass of calcium oxide is required daily to eliminate the sulfur dioxide? (c) How many grams of calcium sulfite are produced daily by this power plant?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
11:34

Problem 110

Copper is an excellent electrical conductor widely used in making electric circuits. In producing a printed circuit board for the electronics industry, a layer of copper is laminated on a plastic board. A circuit pattern is then printed on the board using a chemically resistant polymer. The board is then exposed to a chemical bath that reacts with the exposed copper, leaving the desired copper circuit, which has been protected by the overlaying polymer. Finally, a solvent removes

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:04

Problem 110

Copper is an excellent electrical conductor widely used in making electric circuits. In producing a printed circuit board for the electronics industry, a layer of copper is laminated on a plastic board. A circuit pattern is then printed on the board using a chemically resistant polymer. The board is then exposed to a chemical bath that reacts with the exposed copper, leaving the desired copper circuit, which has been protected by the overlaying polymer. Finally, a solvent removes the polymer. One reaction used to remove the exposed copper from the circuit board is
$$
\begin{aligned}
\mathrm{Cu}(s)+\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}(a q)+4 \mathrm{NH}_{3}(a q) & \longrightarrow \\
& 2 \mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}(a q)
\end{aligned}
$$
A plant needs to produce 5000 circuit boards, each with a surface area measuring 2.0 in. $\times 3.0$ in. The boards are covered with a $0.65-\mathrm{mm}$ layer of copper. In subsequent processing, $85 \%$ of the copper is removed. Copper has a density of $8.96 \mathrm{~g} / \mathrm{cm}^{3} .$ Calculate the masses of $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}$ and $\mathrm{NH}_{3}$
needed to produce the circuit boards, assuming that the reaction used gives a $97 \%$ yield.

Henry He
Henry He
Numerade Educator
12:18

Problem 111

Hydrogen cyanide, HCN, is a poisonous gas. The lethal dose is approximately $300 \mathrm{mg}$ HCN per kilogram of air when inhaled.
(a) Calculate the amount of HCN that gives the lethal dose in a small laboratory room measuring $12 \times 15 \times 8.0 \mathrm{ft}$. The density of air at $26^{\circ} \mathrm{C}$ is $0.00118 \mathrm{~g} / \mathrm{cm}^{3}$.
(b) If the $\mathrm{HCN}$ is formed by reaction of $\mathrm{NaCN}$ with an acid such as $\mathrm{H}_{2} \mathrm{SO}_{4}$, what mass of $\mathrm{NaCN}$ gives the lethal dose in the room?
$2 \mathrm{NaCN}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+2 \mathrm{HCN}(g)$
(c) HCN forms when synthetic fibers containing Orlon $^{\oplus}$ or Acrilan $^{\otimes}$ burn. Acrilan $^{\oplus}$ has an empirical formula of $\mathrm{CH}_{2} \mathrm{CHCN},$ so $\mathrm{HCN}$ is $50.9 \%$ of the formula by mass. $\mathrm{A}$ rug measures $12 \times 15 \mathrm{ft}$ and contains 30 oz of Acrilan $^{\otimes}$ fibers per square yard of carpet. If the rug burns, will a lethal dose of HCN be generated in the room? Assume that the yield of HCN from the fibers is $20 \%$ and that the carpet is $50 \%$ consumed.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
12:18

Problem 112

The source of oxygen that drives the internal combustion engine in an automobile is air. Air is a mixture of gases, principally $\mathrm{N}_{2}(\sim 79 \%)$ and $\mathrm{O}_{2}(\sim 20 \%) .$ In the cylinder of an automobile engine, nitrogen can react with oxygen to produce nitric oxide gas, NO. As $\mathrm{NO}$ is emitted from the tailpipe of the car, it can react with more oxygen to produce nitrogen dioxide gas.
(a) Write balanced chemical equations for both reactions. (b) Both nitric oxide and nitrogen dioxide are pollutants that can lead to acid rain and global warming; collectively, they are called " $\mathrm{NO}_{\mathrm{x}}^{\prime \prime}$ gases. In $2007,$ the United States emitted an estimated 22 million tons of nitrogen dioxide into the atmosphere. How many grams of nitrogen dioxide is this? (c) The production of $\mathrm{NO}_{\mathrm{x}}$ gases is an unwanted side reaction of the main engine combustion process that turns octane, $\mathrm{C}_{8} \mathrm{H}_{18}$, into $\mathrm{CO}_{2}$ and water. If $85 \%$ of the oxygen in an engine is used to combust octane and the remainder used to produce nitrogen dioxide, calculate how many grams of nitrogen dioxide would be produced during the combustion of 500 grams of octane.

Susan Hallstrom
Susan Hallstrom
Numerade Educator