Chemistry for Changing Times

John W. Hill; Terry W. McCreary; Doris K. Kolb

Chapter 5

Chemical Accounting - all with Video Answers

Educators

Chapter Questions

Problem 1

Define or illustrate each of the following.
a. formula unit
b. formula mass
c. mole
d. Avogadro's number
e. molar mass
f. molar volume (of a gas)

Nicole Smina

Nicole Smina

Numerade Educator

Problem 2

Explain the difference between the atomic mass of chlorine and the formula mass of chlorine gas.

Nicole Smina

Numerade Educator

Problem 3

What is Avogadro's hypothesis? How does it explain Gay-Lussac's law of combining volumes?

Nicole Smina

Numerade Educator

Problem 4

Referring to the law of conservation of mass, explain why we must work with balanced chemical equations.

Nicole Smina

Numerade Educator

Problem 5

Define or explain and illustrate the following terms.
a. solution
b. solvent
c. solute
d. aqueous solution

Nicole Smina

Numerade Educator

Problem 6

Define or explain and illustrate the following terms.
a. concentrated solution
b. dilute solution
c. soluble
d. insoluble

Nicole Smina

Numerade Educator

Problem 7

How many oxygen atoms does each of the following contain?
a. $\mathrm{Al}\left(\mathrm{H}_{2} \mathrm{PO}_{4}\right)_{3}$
b. $\mathrm{HOC}_{6} \mathrm{H}_{4} \mathrm{COOCH}_{3}$
c. $(\mathrm{BiO})_{2} \mathrm{SO}_{4}$

Nicole Smina

Numerade Educator

Problem 8

How many carbon atoms does each of the following contain?
a. $\mathrm{Fe}_{2}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}$
b. $\mathrm{Al}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{3}$
c. $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}\left(\mathrm{CH}_{3}\right)_{2}$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 9

How many atoms of each element $(\mathrm{N}, \mathrm{P}, \mathrm{H},$ and O) does the notation $3\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}$ indicate?

Nicole Smina

Numerade Educator

Problem 10

How many atoms of each element $(\mathrm{Cl}, \mathrm{C}, \mathrm{H}, \mathrm{N},$ and O) does the notation $2\left(\mathrm{Cl}-\mathrm{C}_{6} \mathrm{H}_{4} \mathrm{CONH}_{2}\right)$ indicate?

Nicole Smina

Numerade Educator

Problem 11

Consider the following equation. (a) Explain its meaning at the molecular level. (b) Interpret it in terms of moles.
(c) State the mass relationships conveyed by the equation.
$$
2 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}
$$

Nicole Smina

Numerade Educator

Problem 12

Express each chemical equation in terms of moles.
a. $2 \mathrm{Mg}+\mathrm{O}_{2} \longrightarrow 2 \mathrm{MgO}$
b. $2 \mathrm{C}_{2} \mathrm{H}_{6}+7 \mathrm{O}_{2} \longrightarrow 4 \mathrm{CO}_{2}+6 \mathrm{H}_{2} \mathrm{O}$

Nicole Smina

Numerade Educator

Problem 13

Balance the following equations.
a. $\mathrm{Mg}+\mathrm{O}_{2} \longrightarrow \mathrm{MgO}$
b. $\mathrm{C}_{3} \mathrm{H}_{8}+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}$
c. $\mathrm{H}_{2}+\mathrm{Ta}_{2} \mathrm{O}_{3} \longrightarrow \mathrm{Ta}+\mathrm{H}_{2} \mathrm{O}$

Nicole Smina

Numerade Educator

Problem 14

Balance the following equations.
a. $\mathrm{K}+\mathrm{O}_{2} \longrightarrow \mathrm{K}_{2} \mathrm{O}_{2}$
b. $\mathrm{FeCl}_{2}+\mathrm{Na}_{2} \mathrm{SiO}_{3} \longrightarrow \mathrm{NaCl}+\mathrm{FeSiO}_{3}$
c. $\mathrm{F}_{2}+\mathrm{AlCl}_{3} \longrightarrow \mathrm{AlF}_{3}+\mathrm{Cl}_{2}$

Nicole Smina

Numerade Educator

Problem 15

Write balanced equations for the following processes.
a. Nitrogen gas and oxygen gas react to form nitrogen oxide (NO).
b. Ozone $\left(\mathrm{O}_{3}\right)$ decomposes into oxygen gas.
c. Uranium(IV) oxide reacts with hydrogen fluoride (HF) to form uranium(IV) fluoride and water.

Nicole Smina

Numerade Educator

Problem 16

Write balanced equations for the following processes.
a. Iron metal reacts with oxygen gas to form ferric oxide.
b. Magnesium carbonate reacts with hydrochloric acid to form magnesium chloride, water, and carbon dioxide.
c. Butane $\left(\mathrm{C}_{4} \mathrm{H}_{10}\right)$ burns in oxygen gas to form carbon dioxide and water.

Nicole Smina

Numerade Educator

Problem 17

Make a sketch similar to Figure 5.3 to show the reaction of hydrogen gas with oxygen gas to form steam $\left[\mathrm{H}_{2} \mathrm{O}(\mathrm{g})\right]$ at $100^{\circ} \mathrm{C}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 18

Make a sketch similar to Figure 5.3 to show that when hydrogen reacts with oxygen to form steam at $100{ }^{\circ} \mathrm{C}$, each volume of gas-hydrogen, oxygen, or steam-contains the same number of molecules.

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 19

Consider the following equation, which represents the combustion (burning) of methane $\left(\mathrm{CH}_{4}\right)$.
$$
\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})
$$
a. What volume, in liters, of $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ is formed when 10.6 L of $\mathrm{CH}_{4}(\mathrm{~g})$ is burned? Assume that both gases are measured under the same conditions.
b. What volume, in milliliters, of $\mathrm{CH}_{4}(\mathrm{~g})$ has to burn to react with $27.0 \mathrm{~mL} \mathrm{O}_{2}(\mathrm{~g}) ?$ Assume that both gases are measured under the same conditions.

Nicole Smina

Numerade Educator

Problem 20

Consider the following equation, which represents the combustion of ammonia.
$$
\left.4 \mathrm{NH}_{3}(\mathrm{~g})+3 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{~N}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{Og}\right)
$$
a. What volume, in liters, of $\mathrm{N}_{2}(\mathrm{~g})$ is formed when $127 \mathrm{~L}$ of $\mathrm{NH}_{3}(\mathrm{~g})$ is burned? Assume that both gases are measured under the same conditions.
b. What volume, in liters, of $\mathrm{O}_{2}(\mathrm{~g})$ is required to form $43 \mathrm{~L}$ of $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ ? Assume that both gases are measured under the same conditions.

Nicole Smina

Numerade Educator

Problem 21

Using the equation in Problem 19 , determine the ratio of volume of $\mathrm{CO}_{2}(\mathrm{~g})$ formed to volume of $\mathrm{C}_{6} \mathrm{H}_{14}(\mathrm{~g})$ that reacts, assuming that both gases are measured under the same conditions.

Nicole Smina

Numerade Educator

Problem 22

Using the equation in Problem $20,$ determine the ratio of volume of $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ formed to volume of $\mathrm{NH}_{3}(\mathrm{~g})$ that reacts, assuming that both gases are measured under the same conditions.

Nicole Smina

Numerade Educator

Problem 23

How many (a) sulfur molecules and how many (b) sulfur atoms are there in $1.00 \mathrm{~mol} \mathrm{~S}_{8} ?$

Nicole Smina

Numerade Educator

Problem 24

How many (a) magnesium ions and how many (b) nitride ions are there in $1.00 \mathrm{~mol} \mathrm{Mg}_{3} \mathrm{~N}_{2} ?$

Nicole Smina

Numerade Educator

Problem 25

Choose one of the following to complete this statement correctly: One mole of bromine $\left(\mathrm{Br}_{2}\right)$ gas ______________ .
a. has a mass of $79.9 \mathrm{~g}$
b. contains $6.02 \times 10^{23} \mathrm{Br}$ atoms
c. contains $12.04 \times 10^{23} \mathrm{Br}$ atoms
d. has a mass of $6.02 \times 10^{23} \mathrm{~g}$

Nicole Smina

Numerade Educator

Problem 26

(a) How many barium ions and how many nitrate ions are there in $3.10 \mathrm{~mol} \mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2} ?$ (b) How many nitrate atoms and how many oxygen atoms are there in $3.10 \mathrm{~mol}$ $\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2} ?$

Nicole Smina

Numerade Educator

Problem 27

Calculate the molar mass of each of the following compounds.
a. $\mathrm{AgNO}_{3}$
b. $\mathrm{Mg}(\mathrm{CIO})_{2}$
c. $\mathrm{Zn}\left(\mathrm{lO}_{4}\right)_{2}$
d. $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{COF}$

Nicole Smina

Numerade Educator

Problem 28

Calculate the molar mass of each of the following compounds.
a. $\mathrm{Bi}_{2} \mathrm{O}_{3}$
b. $\mathrm{FeSO}_{4}$
c. $\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{2}$
d. $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 29

Calculate the mass, in grams, of each of the following.
a. $7.57 \mathrm{~mol} \mathrm{BaSO}_{4}$
b. $0.0472 \mathrm{~mol}$
c. $0.250 \mathrm{~mol} \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 30

Calculate the mass, in grams, of each of the following
a. $4.61 \mathrm{~mol} \mathrm{PCl}_{3}$
b. $6.15 \mathrm{~mol} \mathrm{Cr}_{2} \mathrm{O}_{3}$
c. $0.158 \mathrm{~mol} \mathrm{IF}_{5}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 31

Calculate the amount, in moles, of each of the following.
a. $6.63 \mathrm{~g} \mathrm{Sb}_{2} \mathrm{~S}_{3}$
b. $19.1 \mathrm{~g} \mathrm{MoO}_{3}$
c. $434 \mathrm{~g} \mathrm{AlPO}_{4}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 32

Calculate the amount, in moles, of each of the following.
a. $16.3 \mathrm{~g} \mathrm{SF}_{6}$
b. $25.4 \mathrm{~g} \mathrm{~Pb}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}$
c. $15.6 \mathrm{~g}$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 33

Calculate the percent by mass of $\mathrm{N}$ in
(a) $\mathrm{NaNO}_{3}$, and
(b) $\mathrm{NH}_{4} \mathrm{Cl}$.

Nicole Smina

Numerade Educator

Problem 34

Calculate the percent by mass of $\mathrm{C}, \mathrm{H},$ and $\mathrm{O}$ in sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$

Nicole Smina

Numerade Educator

Problem 35

Consider the reaction for the combustion of butane $\left(\mathrm{C}_{4} \mathrm{H}_{10}\right),$ a component of liquefied petroleum (LP) gas.
$$
2 \mathrm{C}_{4} \mathrm{H}_{10}(\mathrm{~g})+13 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 8 \mathrm{CO}_{2}(\mathrm{~g})+10 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})
$$
a. How many moles of $\mathrm{CO}_{2}$ are produced when $0.845 \mathrm{~mol}$ of butane are burned?
b. How many moles of oxygen are required to burn 2.54 mol of butane?

Nicole Smina

Numerade Educator

Problem 36

Consider the reaction for the combustion of octane $\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)$.
$$
2 \mathrm{C}_{8} \mathrm{H}_{18}+25 \mathrm{O}_{2} \longrightarrow 16 \mathrm{CO}_{2}+18 \mathrm{H}_{2} \mathrm{O}
$$
a. How many moles of $\mathrm{H}_{2} \mathrm{O}$ are produced when $0.281 \mathrm{~mol}$ of octane is burned?
b. How many moles of $\mathrm{CO}_{2}$ are produced when $8.12 \mathrm{~mol}$ of oxygen reacts with octane?

Nicole Smina

Numerade Educator

Problem 37

What mass in grams (a) of ammonia can be made from $250 \mathrm{~g}$ of $\mathrm{H}_{2}$ and (b) of hydrogen is needed to react completely with $923 \mathrm{~g} \mathrm{~N}_{2} ?$
$$
\mathrm{N}_{2}+\mathrm{H}_{2} \longrightarrow \mathrm{NH}_{3} \quad \text { (not balanced) }
$$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 38

Toluene $\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)$ and nitric acid $\left(\mathrm{HNO}_{3}\right)$ are used in the production of trinitrotoluene $\left(\mathrm{TNT}, \mathrm{C}_{7} \mathrm{H}_{5} \mathrm{~N}_{3} \mathrm{O}_{6}\right), \quad$ an
explosive.
$$
\mathrm{C}_{7} \mathrm{H}_{8}+\mathrm{HNO}_{3} \longrightarrow \mathrm{C}_{7} \mathrm{H}_{5} \mathrm{~N}_{3} \mathrm{O}_{6}+\mathrm{H}_{2} \mathrm{O} \quad \text { (not balanced) }
$$
What mass in grams (a) of nitric acid is required to react with $432 \mathrm{~g}$ and (b) of TNT can be made from $584 \mathrm{~g} \mathrm{C}_{7} \mathrm{H}_{8} ?$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 39

Calculate the molarity of each of the following solutions.
a. $23.4 \mathrm{~mol} \mathrm{HCl}$ in $10.0 \mathrm{~L}$ of solution
b. $0.0875 \mathrm{~mol} \mathrm{Li}_{2} \mathrm{CO}_{3}$ in $632 \mathrm{~mL}$ of solution

Nicole Smina

Numerade Educator

Problem 40

Calculate the molarity of each of the following solutions.
a. $23.4 \mathrm{~mol} \mathrm{HCl}$ in $10.0 \mathrm{~L}$ of solution
b. $0.0875 \mathrm{~mol} \mathrm{Li}_{2} \mathrm{CO}_{3}$ in $632 \mathrm{~mL}$ of solution

Nicole Smina

Numerade Educator

Problem 41

What mass in grams of solute is needed to prepare
(a) $3.50 \mathrm{~L}$ of $0.500 \mathrm{M} \mathrm{NaOH}$ and
(b) $65.0 \mathrm{~mL}$ of $1.45 \mathrm{M}$
$\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} ?$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 42

What mass in grams of solute is needed to prepare
(a) $0.250 \mathrm{~L}$ of $0.167 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ and
(b) $625 \mathrm{~mL}$ of $0.0200 \mathrm{M}$
$\mathrm{KMnO}_{4} ?$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 43

What volume in liters of (a) $3.00 \mathrm{MKOH}$ contains $12.50 \mathrm{~mol}$ $\mathrm{KOH}$ and (b) $0.0500 \mathrm{M} \mathrm{KHSO}_{4}$ contains $8.10 \mathrm{~g} \mathrm{KHSO}_{4} ?$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 44

What volume in liters of
(a) $0.250 \mathrm{M} \mathrm{NaOH}$ contains 2.50 $\mathrm{M} \mathrm{NaOH}$ and
(b) $4.25 \mathrm{M} \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$ contains $0.225 \mathrm{~g} \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} ?$

Crystal Wang

Numerade Educator

Problem 45

What is the percent by volume concentration of (a) $58.0 \mathrm{~mL}$ of water in $625 \mathrm{~mL}$ of an acetic acid-water solution and
(b) $79.1 \mathrm{~mL}$ of methanol in $755 \mathrm{~mL}$ of a methanol-water solution?

Crystal Wang

Numerade Educator

Problem 46

What is the percent by volume concentration of (a) $35.0 \mathrm{~mL}$ of water in $725 \mathrm{~mL}$ of an ethanol-water solution and
(b) $78.9 \mathrm{~mL}$ of acetone in $1550 \mathrm{~mL}$ of an acetone-water solution?

Crystal Wang

Numerade Educator

Problem 47

Describe how you would prepare $3375 \mathrm{~g}$ of an aqueous solution that is $8.2 \% \mathrm{NaCl}$ by mass.

Crystal Wang

Numerade Educator

Problem 48

Describe how you would prepare $2.44 \mathrm{~kg}$ of an aqueous solution that is $16.3 \% \mathrm{KOH}$ by mass.

Crystal Wang

Numerade Educator

Problem 49

Describe how you would prepare $2.00 \mathrm{~L}$ of an aqueous solution that is $2.00 \%$ acetic acid by volume.

Crystal Wang

Numerade Educator

Problem 50

Describe how you would prepare $600.0 \mathrm{~mL}$ of an aqueous solution that is $30.0 \%$ isopropyl alcohol by volume.

Ronald Prasad

Numerade Educator

Problem 51

Both magnesium and aluminum react with hydrogen ions in aqueous solution to produce hydrogen. Why is it that only one of the following equations correctly describes the reaction?
$$
\begin{aligned}
\mathrm{Mg}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow \mathrm{Mg}^{2+}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g}) \\
\mathrm{Al}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow \mathrm{Al}^{3+}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})
\end{aligned}
$$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 52

Which of the following correctly represents the decomposition of potassium chlorate to produce potassium chloride and oxygen gas?
a. $\mathrm{KClO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{KClO}_{3}(\mathrm{~s})+\mathrm{O}_{2}(\mathrm{~g})+\mathrm{O}(\mathrm{g})$
b. $2 \mathrm{KClO}_{3}(\mathrm{~s}) \longrightarrow 2 \mathrm{KCl}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{~g})$
c. $\mathrm{KClO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{KClO}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g})$
d. $\mathrm{KClO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{KCl}(\mathrm{s})+\mathrm{O}_{3}(\mathrm{~g})$

Nicole Smina

Numerade Educator

Problem 53

Write a balanced chemical equation to represent (a) the decomposition, by heating, of solid mercury(II) nitrate to produce pure liquid mercury, nitrogen dioxide gas, and oxygen gas, and (b) the reaction of aqueous sodium carbonate with aqueous hydrochloric acid (hydrogen chloride) to produce water, carbon dioxide gas, and aqueous sodium chloride.

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 54

Joseph Priestley discovered oxygen in 1774 by heating "red calx of mercury" [mercury(II) oxide]. The calx decomposed to its elements. The equation is
$$
\mathrm{HgO} \longrightarrow \mathrm{Hg}+\mathrm{O}_{2} \quad \text { (not balanced) }
$$
What mass of oxygen is produced by the decomposition of $18.0 \mathrm{~g} \mathrm{HgO} ?$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 55

Consider $1.00 \mathrm{~mol} \mathrm{H}_{2}(\mathrm{~g}), 2.00 \mathrm{~mol} \mathrm{He}(\mathrm{g}),$ and $0.50 \mathrm{~mol}$
$\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})$ at the same temperature and pressure. (a) Do the three samples have the same number of atoms? (b) Which sample has the greatest mass?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 56

What mass in grams of the magnetic oxide of iron $\left(\mathrm{Fe}_{3} \mathrm{O}_{4}\right)$ can be made from $50.0 \mathrm{~g}$ of pure iron and an excess of oxygen? The equation is
$$
\mathrm{Fe}+\mathrm{O}_{2} \longrightarrow \mathrm{Fe}_{3} \mathrm{O}_{4} \quad \text { (not balanced) }
$$

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 57

When heated above $\sim 900^{\circ} \mathrm{C}$, limestone (calcium carbonate) decomposes to quicklime (calcium oxide), which is used to make cement, and carbon dioxide. What mass in grams of quicklime can be produced from $2.5 \times 10^{5} \mathrm{~g}$ of limestone?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 58

Ammonia reacts with oxygen to produce nitric acid $\left(\mathrm{HNO}_{3}\right)$ and water. What mass of nitric acid, in grams, can be made from $549 \mathrm{~g}$ of ammonia?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 59

Hydrogen peroxide solution sold in drugstores is $3.0 \%$ $\mathrm{H}_{2} \mathrm{O}_{2}$ by mass dissolved in water. How many moles of $\mathrm{H}_{2} \mathrm{O}_{2}$ are in a typical 16 -fl. oz bottle of this solution? (1 fl. oz $=29.6 \mathrm{~mL} ;$ density $=1.00 \mathrm{~g} / \mathrm{mL})$

Crystal Wang

Numerade Educator

Problem 60

What is the mass percent of (a) $\mathrm{NaOH}$ in a solution of $2.59 \mathrm{~g} \mathrm{NaOH}$ in $100.0 \mathrm{~g}$ of water and (b) ethanol in a solution of $5.25 \mathrm{~mL}$ of ethanol (density $=0.789 \mathrm{~g} / \mathrm{mL}$ ) in 50.0 g of water?

Crystal Wang

Numerade Educator

Problem 61

What is the volume percent of (a) ethanol in $355 \mathrm{~mL}$ of an ethanol-water solution that contains $18.0 \mathrm{~mL}$ of water
and (b) acetone in 1.55 L of an acetone-water solution that contains $4.00 \mathrm{~mL}$ of acetone?

Crystal Wang

Numerade Educator

Problem 62

Laughing gas (dinitrogen monoxide, $\mathrm{N}_{2} \mathrm{O}$; also called nitrous oxide) can be made by very carefully heating ammonium nitrate. The other product is water.
a. Write a balanced equation for the process.
b. Draw the Lewis structure for $\mathrm{N}_{2} \mathrm{O}$.
c. What mass in grams of $\mathrm{N}_{2} \mathrm{O}$ can be made from $150.0 \mathrm{~g}$ of ammonium nitrate?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 63

In Table 1.6 we listed some multiplicative prefixes used with SI base units. In the $1990 \mathrm{~s}$, some new prefixes were recommended:
zetta- $\left(\mathrm{Z}, 10^{21}\right) \quad$ yotta $-\left(\mathrm{Y}, 10^{24}\right)$
zepto- $\left(\mathrm{z}, 10^{-21}\right) \quad$ yocto- $\left(\mathrm{y}, 10^{-24}\right)$
a. What is the mass of 1.50 ymol of uranium in yoctograms?
b. How many atoms are in $1.20 \mathrm{zmol}$ of uranium?

Crystal Wang

Numerade Educator

Problem 64

What volume of $0.859 \mathrm{M}$ oxalic acid contains $31.7 \mathrm{~g}$ of oxalic acid $\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\right) ?$

Crystal Wang

Numerade Educator

Problem 65

In tests for intoxication, blood alcohol levels are expressed as percentages by volume. A blood alcohol level of $0.080 \%$ by volume means $0.080 \mathrm{~mL}$ of ethanol per $100 \mathrm{~mL}$ of blood and is considered proof of intoxication. If a person's total blood volume is $5.0 \mathrm{~L},$ what volume of alcohol in the blood gives a blood alcohol level of $0.165 \%$ by volume?

Crystal Wang

Numerade Educator

Problem 66

Homeopathic remedies are prepared by using a process of dilution, starting with a substance that causes symptoms of the illness being treated. Some homeopaths use a scale $(\mathrm{X})$ in which the substance is diluted by a factor of ten at each stage. For example, for a $6 \mathrm{X}$ remedy, the original substance is diluted tenfold six times, for a total dilution of $10^{6}$. (Many homeopathic remedies are diluted far more than six times.)
a. If the original substance is in the form of a $1.00 \mathrm{M}$ solution, what would be the yoctomolar concentration of a $24 \mathrm{X}$ remedy? (Few starting solutions are $1 \mathrm{M} ;$ most are far less concentrated.)
b. How many molecules of the original substance remain in $1.00 \mathrm{~L}$ of a $24 \mathrm{X}$ remedy?

Crystal Wang

Numerade Educator

Problem 67

Evaluate this statement: "One cup of water has more molecules than there are cups of water in all of Earth's oceans" $\left(1 \mathrm{cup}=236 \mathrm{~mL}=236 \mathrm{~cm}^{3}\right)$. For the volume of the oceans, use $3.50 \times 10^{8}$ cubic miles.

Crystal Wang

Numerade Educator

Problem 68

If a Neanderthal excreted $500 \mathrm{~mL}$ of urine into the ocean 50,000 years ago, how many molecules in $500 \mathrm{~mL}$ of water you drink today are from that urine? Refer to Problem 67 and assume complete mixing of the waters of Earth over 50,000 years.

Crystal Wang

Numerade Educator

Problem 69

A truck carrying about $5.41 \times 10^{4} \mathrm{~kg}$ of sulfuric acid $\left(\mathrm{H}_{2} \mathrm{SO}_{4}\right)$ is involved in an accident, spilling the acid. What mass of sodium bicarbonate $\left(\mathrm{NaHCO}_{3}\right)$ is needed to react with and neutralize the sulfuric acid? The products of the reaction are sodium sulfate $\left(\mathrm{Na}_{2} \mathrm{SO}_{4}\right),$ water, and carbon dioxide.

Crystal Wang

Numerade Educator

Problem 70

Referring to Problem 69 , determine the mass of sodium carbonate $\left(\mathrm{Na}_{2} \mathrm{CO}_{3}\right)$ needed to neutralize the acid. (The products of the reaction are the same.)

Crystal Wang

Numerade Educator

Problem 71

How many moles of $\mathrm{H}_{2} \mathrm{O}$ are in $2.00 \mathrm{~L}$ of water? $(\mathrm{d}=1.00 \mathrm{~g} / \mathrm{mL})$

Nicole Smina

Numerade Educator

Problem 72

Consider the following equation for the reaction of sodium azide that forms nitrogen gas in airbags. (a) What is the atom economy for the production of $\mathrm{N}_{2} ?$ (b) What is the mass in grams of $\mathrm{N}_{2}$ that is formed if $5.74 \mathrm{~g}$ of $\mathrm{NaN}_{3}$ are reacted?
$$
2 \mathrm{NaN}_{3} \longrightarrow 2 \mathrm{Na}+3 \mathrm{~N}_{2}
$$

Crystal Wang

Numerade Educator

Problem 73

Ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is a very important chemical. In addition to being widely used as an industrial solvent, a gasoline additive, and an alternative fuel, it is well known as the alcohol in alcoholic beverages. A common name for ethanol is grain alcohol because it is formed by the fermentation of glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ and other sugars in grains such as corn, wheat, and barley:
$$
\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{CO}_{2}
$$
The previous reaction has been carried out for many centuries and is one of the oldest manufacturing processes. In a more recent development, ethanol can be prepared by reacting ethylene (found in petroleum) with water:
$$
\mathrm{C}_{2} \mathrm{H}_{4}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}
$$
a. Write the balanced equation for each of the two reactions above.
b. Calculate the $\%$ A.E. (for the product ethanol) for each of the two reactions.
c. Explain how you can determine which reaction has the higher atom economy without doing the calculation in part (b) above.
d. Is either method sustainable? Which one? Justify your
answer.
e. Given the results from parts (b) and (d) above, select one of the two methods as the better candidate overall for preparing ethanol. Justify your selection.

Crystal Wang

Numerade Educator

Problem 74

Consider the following equation for the formation of carbon dioxide $\mathrm{CO}_{2}$, a known greenhouse gas, from the combustion of hydrocarbons.
$$
\mathrm{C}_{5} \mathrm{H}_{12}+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \quad \text { (not balanced) }
$$
a. What is the percent atom economy based on carbon dioxide as the target product?
b. How many grams of $\mathrm{CO}_{2}$ form if $10.0 \mathrm{~g} \mathrm{C}_{5} \mathrm{H}_{12}$ is burned?
c. What is the percent yield of the reaction if $25.4 \mathrm{~g} \mathrm{CO}_{2}$ are formed at the end of the reaction? (Hint: Use the information in the Atom Economy essay for this calculation.)

Crystal Wang

Numerade Educator

Problem 75

Consider the following equation for the formation of carbon dioxide $\mathrm{CO}_{2}$, a known greenhouse gas, from the combustion of hydrocarbons.
$$
\mathrm{C}_{5} \mathrm{H}_{12}+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \quad \text { (not balanced) }
$$
a. What is the percent atom economy based on carbon dioxide as the target product?
b. How many grams of $\mathrm{CO}_{2}$ form if $10.0 \mathrm{~g} \mathrm{C}_{5} \mathrm{H}_{12}$ is burned?
c. What is the percent yield of the reaction if $25.4 \mathrm{~g} \mathrm{CO}_{2}$ are formed at the end of the reaction? (Hint: Use the information in the Atom Economy essay for this calculation.)

Crystal Wang

Numerade Educator