Chemistry Matter and Change

Thandi Buthelezi, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom, Dinah Zike

Chapter 11

Stoichiometry - all with Video Answers

Educators

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Chapter Questions

Problem 1

Interpret the following balanced chemical equations in terms of particles, moles, and
mass. Show that the law of conservation of mass is observed.
\begin{equation}
\begin{array}{l}{\text { a. } \mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{g})} \\ {\text { b. } \mathrm{HCl}(\mathrm{aq})+\mathrm{KOH}(\mathrm{aq}) \rightarrow \mathrm{KCl}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})} \\ {\text { c. } 2 \mathrm{Mg}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{MgO}(\mathrm{s})}\end{array}
\end{equation}

Ronald Prasad

Ronald Prasad

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Problem 2

Challenge For each of the following, balance the chemical equation; interpret the
equation in terms of particles, moles, and mass; and show that the law of conservation
of mass is observed.
a. ___$\mathrm{Na}(\mathrm{s})+$____$\mathrm{H}_{2} \mathrm{O}(1) \rightarrow$____$\mathrm{NaOH}(\mathrm{aq})+$____$\mathrm{H}_{2}(\mathrm{g})$
b.___$Z n(s)+$____$\mathrm{HNO}_{3}(\mathrm{aq}) \rightarrow$____$\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+$____$\mathrm{N}_{2} \mathrm{O}(\mathrm{g})+$____$\mathrm{H}_{2} \mathrm{O}(\mathfrak{l})$

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 3

Determine all possible mole ratios for the following balanced chemical equations.
\begin{equation}
\begin{array}{l}{\text { a. } 4 \mathrm{Al}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{s})} \\ {\text { b. } 3 \mathrm{Fe}(\mathrm{s})+4 \mathrm{H}_{2} \mathrm{O}\left(\mathrm{l} \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}(\mathrm{s})+4 \mathrm{H}_{2}(\mathrm{g})\right.} \\ {\text { c. } 2 \mathrm{HgO}(\mathrm{s}) \rightarrow 2 \mathrm{Hg}(1)+\mathrm{O}_{2}(\mathrm{g})}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 4

Challenge Balance the following equations, and determine the possible mole ratios.
\begin{equation}
\begin{array}{l}{\text { a. } \mathrm{ZnO}(\mathrm{s})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{ZnCl}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})} \\ {\text { b. butane }\left(\mathrm{C}_{4} \mathrm{H}_{10}\right)+\text { oxygen } \rightarrow \text { carbon dioxide }+\text { water }}\end{array}
\end{equation}

Cheryl Glor

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Problem 5

Compare the mass of the reactants and the mass of the products
in a chemical reaction, and explain how these masses are related.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 6

State how many mole ratios can be written for a chemical reaction involving
three substances.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 7

Categorize the ways in which a balanced chemical equation can be interpreted.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 8

Apply The general form of a chemical reaction is $x A+y B \rightarrow z A B$ . In the equa-
tion, $A$ and $B$ are elements, and $x_{i} y$ , and $z$ are coefficients. State the mole ratios
for this reaction.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 9

Apply Hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)$ decomposes to produce water and oxygen.
Write a balanced chemical equation for this reaction, and determine the possible
mole ratios.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 10

Model Write the mole ratios for the reaction of hydrogen gas and oxygen gas,
$2 \mathrm{H}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{H}_{2} 0 .$ Make a sketch of six hydrogen molecules reacting with
the correct number of oxygen molecules. Show the water molecules produced.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 11

Methane and sulfur react to produce carbon disulfide $\left(\mathrm{CS}_{2}\right),$ a liquid
often used in the production of cellophane.
___$\mathrm{CH}_{4}(\mathrm{g})+$ ___ $\mathrm{S}_{8}(\mathrm{s}) \rightarrow$ ___$\mathrm{cs}_{2}(\mathrm{l})$ + ___ $\mathrm{H}_{2} \mathrm{S}(\mathrm{g})$
\begin{equation}
\begin{array}{l}{\text { a. Balance the equation. }} \\ {\text { b. Calculate the moles of } \mathrm{CS}_{2} \text { produced when } 1.50 \mathrm{mol} \mathrm{S}_{8} \text { is used. }} \\ {\text { c. How many moles of } \mathrm{H}_{2} \mathrm{S} \text { is produced? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 12

Challenge Sulfuric acid $\left(\mathrm{H}_{2} \mathrm{SO}_{\mathfrak{4}}\right)$ is formed when sulfur dioxide $\left(\mathrm{SO}_{2}\right)$
reacts with oxygen and water.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. How many moles of } \mathrm{H}_{2} \mathrm{SO}_{4} \text { is produced from } 12.5 \text { moles of } \mathrm{SO}_{2} \text { ? }} \\ {\text { c. How many moles of } \mathrm{O}_{2} \text { are needed? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 13

Sodium chloride is decomposed into the elements sodium and chlorine
by means of electrical energy. How much chlorine gas, in grams, is obtained
from the process diagrammed at right?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 14

Challenge Titanium is a transition metal used in many alloys because it is extremely strong and lightweight. Titanium tetrachloride $(\mathrm{TiCl_{4 }})$ is
extracted from titanium oxide $\left(\mathrm{TiO}_{2}\right)$ using chlorine and coke (carbon).
$$\mathrm{TiO}_{2}(\mathrm{s})+\mathrm{C}(\mathrm{s})+2 \mathrm{Cl}_{2}(\mathrm{g}) \rightarrow \mathrm{TiCl}_{4}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})$$
\begin{equation}
\mathrm{a. Cl}_{2} \text { gas is needed to react with } 1.25 \text { mol of } \mathrm{TIO}_{2} ?
\end{equation}
\begin{equation}
\begin{array}{l}{\text { b. What mass of } C \text { is needed to react with } 1.25 \text { mol of TiO_{2} ? }} \\ {\text { c. What is the mass of all of the products formed by reaction with } 1.25 \text { mol of TiO_{2} ? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 15

One of the reactions used to inflate automobile air bags involves
sodium azide $\left(\mathrm{NaN}_{3}\right) : 2 \mathrm{NaN}_{3}(\mathrm{s}) \rightarrow 2 \mathrm{Na}(\mathrm{s})+3 \mathrm{N}_{2}(\mathrm{g}) .$ Determine the mass of $\mathrm{N}_{2}$ produced from the decomposition of $\mathrm{NaN}_{3}$ shown at right.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 16

Challenge In the formation of acid rain, sulfur dioxide $\left(\mathrm{SO}_{2}\right)$ reacts with
oxygen and water in the air to form sulfuric acid $\left(\mathrm{H}_{2} \mathrm{SO}_{4}\right) .$ Write the balanced chemical equation for the reaction. If 2.50 $\mathrm{g}$ of $\mathrm{SO}_{2}$ reacts with excess oxygen and water, how much $\mathrm{H}_{2} \mathrm{SO}_{4}$ , in grams, is produced?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 17

Explain why a balanced chemical equation is needed to solve a stoichiometric problem.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 18

List the four steps used in solving stoichiometric problems.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 19

Describe how a mole ratio is correctly expressed when it is used to solve a stoichiometric problem.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 20

Apply How can you determine the mass of liquid bromine $\left(B r_{2}\right)$ needed to react
completely with a given mass of magnesium?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 21

Calculate Hydrogen reacts with excess nitrogen as follows:
\begin{equation}
\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{g})
\end{equation}
If 2.70 gof $H_{2}$ reacts, how many grams of $\mathrm{NH}_{3}$ is formed?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 22

Design a concept map for the following reaction.
\begin{equation}
\mathrm{CaCO}_{3}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{CaC}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathfrak{l})+\mathrm{CO}_{2}(\mathrm{g})
\end{equation}
The concept map should explain how to determine the mass of $\mathrm{CaCl}_{2}$ produced
from a given mass of HCl.

Lijeesh Krishnan

Lijeesh Krishnan

Numerade Educator

Problem 23

The reaction between solid sodium and iron(llI) oxide is one in a series of reactions that
inflates an automobile airbag: $6 \mathrm{Na}(\mathrm{s})+\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s}) \rightarrow 3 \mathrm{Na}_{2} \mathrm{O}(\mathrm{s})+2 \mathrm{Fe}(\mathrm{s}) .$ If 100.0 $\mathrm{g}$ of $\mathrm{Na}$
and 100.0 $\mathrm{g}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ are used in this reaction, determine the following.
\begin{equation}
\begin{array}{l}{\text { a. limiting reactant }} \\ {\text { b. reactant in excess }} \\ {\text { c. mass of solid iron produced }} \\ {\text { d. mass of excess reactant that remains after the reaction is complete }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 24

Challenge Photosynthesis reactions in green plants use carbon dioxide and water
to produce glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ and oxygen. A plant has 88.0 $\mathrm{g}$ of carbon dioxide and
64.0 $\mathrm{g}$ of water available for photosynthesis.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. Determine the limiting reactant. }} \\ {\text { c. Determine the excess reactant. }} \\ {\text { d. Determine the mass in excess. }} \\ {\text { e. Determine the mass of glucose produced. }}\end{array}
\end{equation}

Meet Surti

Numerade Educator

Problem 25

Describe the reason why a reaction between two substances
comes to an end.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 26

Identify the limiting and the excess reactant in each reaction.
\begin{equation}
\begin{array}{l}{\text { a. Wood burns in a campfire. }} \\ {\text { b. Airborne sulfur reacts with the silver plating on a teapot to produce tarnish }} \\ {\text { (silver sulfide). }} \\ {\text { C. Baking powder in batter decomposes to produce carbon dioxide. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 27

Analyze Tetraphosphorus trisulphide $\left(P_{4} S_{3}\right)$ is used in the match heads of some
matches. It is produced in the reaction $8 \mathrm{P}_{4}+3 \mathrm{S}_{8} \rightarrow 8 \mathrm{P}_{4} \mathrm{S}_{3}$ . Determine which of the following statements are incorrect, and rewrite the incorrect statements to make them correct.
\begin{equation}
\begin{array}{l}{\text { a. } 4 \text { mol } P_{4} \text { reacts with } 1.5 \text { mol } S_{8} \text { to form } 4 \text { mol } P_{4} S_{3} \text { . }} \\ {\text { b. Sulfur is the limiting reactant when } 4 \text { mol } P_{4} \text { and } 4 \text { mol } S_{8} \text { react. }} \\ {\text { c. } 6 \text { mol } P_{4} \text { reacts with } 6 \text { mol } S_{8} \text { forming } 1320 \text { g } P_{4} S_{3} \text { . }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 28

Aluminum hydroxide $\left(\mathrm{Al}(\mathrm{OH})_{3}\right)$ is often present in antacids to
neutralize stomach acid (HCl). The reaction occurs as follows:
$\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})+3 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{AlCl}_{3}(\mathrm{aq})+3 \mathrm{H}_{2} \mathrm{O}(1) .$ If 14.0 $\mathrm{g}$ of $\mathrm{Al}(\mathrm{OH})_{3}$ is present in an antacid tablet, determine the theoretical yield of
AlCl_ produced when the tablet reacts with HCl.

Ronald Prasad

Numerade Educator

Problem 29

Zinc reacts with iodine in a synthesis reaction: $\mathrm{Zn}+\mathrm{I}_{2} \rightarrow \mathrm{ZnI}_{2}$
\begin{equation}
\begin{array}{l}{\text { a. Determine the theoretical yield if } 1.912 \text { mol of zinc is used. }} \\ {\text { b. Determine the percent yield if } 515.6 \mathrm{g} \text { of product is recovered. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 30

Challenge When copper wire is placed into a silver nitrate solution
$\left(\mathrm{AgNO}_{3}\right),$ silver crystals and copper(ll) nitrate $\left(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\right)$ solution
form.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. If a } 20.0 \text { -g sample of copper is used, determine the theoretical yield }} \\ {\text { of silver. }} \\ {\text { c. If } 60.0 \text { g of silver is recovered from the reaction, determine the }} \\ {\text { percent yield of the reaction. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 31

Identify which type of yield-theoretical yield, actual yield, or
percent yield-is a measure of the efficiency of a chemical reaction.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 32

List several reasons why the actual yield from a chemical reaction is not usually
equal to the theoretical yield.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 33

Explain how percent yield is calculated.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 34

Apply In an experiment, you combine 83.77 $\mathrm{g}$ of iron with an excess of sulfur
and then heat the mixture to obtain iron(lil) sulfide.
$$2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{S}(\mathrm{s}) \rightarrow \mathrm{Fe}_{2} \mathrm{S}_{3}(\mathrm{s})$$
What is the theoretical yield, in grams, of iron(III) sulfide?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 35

Calculate the percent yield of the reaction of magnesium with excess oxygen:
$2 \mathrm{Mg}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{MgO}(\mathrm{s})$

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 36

Why must a chemical equation be balanced before you
can determine mole ratios?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 37

What relationships can be determined from a balanced
chemical equation?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 38

Explain why mole ratios are central to stoichiometric
calculations.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 39

What is the mole ratio that can convert from moles of A
to moles of B?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 40

Why are coefficients used in mole ratios instead of
subscripts?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 41

Explain how the conservation of mass allows you to
interpret a balanced chemical equation in terms of mass.

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 42

When heated by a flame, ammonium dichromate
decomposes, producing nitrogen gas, solid
chromium(III) oxide, and water vapor
\begin{equation}
\left(\mathrm{NH}_{4}\right) 2 \mathrm{Cr}_{2} \mathrm{O}_{7} \rightarrow \mathrm{N}_{2}+\mathrm{Cr}_{2} \mathrm{O}_{3}+4 \mathrm{H}_{2} \mathrm{O}
\end{equation}
Write the mole ratios for this reaction that relate ammonium dichromate to the products.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 43

Figure 11.10 depicts an equation with squares representing Element $M$ and circles representing Element $N$
Write a balanced equation to represent the picture
shown, using smallest whole-number ratios. Write mole
ratios for this equation.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 44

Interpret the following equation in terms of particles, moles, and mass.
\begin{equation}
4 \mathrm{Al}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{s})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 45

Smelting When tin(IV) oxide is heated with carbon
in a process called smelting, the element tin can be
extracted.
\begin{equation}
\mathrm{SnO}_{2}(\mathrm{s})+2 \mathrm{C}(\mathrm{s}) \rightarrow \mathrm{Sn}(1)+2 \mathrm{CO}(\mathrm{g})
\end{equation}
Interpret the chemical equation in terms of particles, moles, and mass.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 46

When solid copper is added to nitric acid, copper(II)
nitrate, nitrogen dioxide, and water are produced.
Write the balanced chemical equation for the reaction.
List six mole ratios for the reaction.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 47

When hydrochloric acid solution reacts with lead(II)
nitrate solution, lead(II) chloride precipitates and a
solution of nitric acid is produced.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. Interpret the equation in terms of molecules and }} \\ {\text { formula units, moles, and mass. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 48

When aluminum is mixed with iron (III) oxide, iron
metal and aluminum oxide are produced, along with a
large quantity of heat. What mole ratio would you use
to determine moles of Fe if moles of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is known?
\begin{equation}
\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+2 \mathrm{Al}(\mathrm{s}) \rightarrow 2 \mathrm{Fe}(\mathrm{s})+\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{s})+ heat\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 49

Solid silicon dioxide, often called silica, reacts with
hydrofluoric acid (HF) solution to produce the gas
silicon tetrafluoride and water.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. List three mole ratios, and explain how you would use }} \\ {\text { them in stoichiometric calculations. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 50

Chrome The most important commercial ore of chromium is chromite $\left(\mathrm{FeCr}_{2} \mathrm{O}_{4}\right) .$ One of the steps in the
process used to extract chromium from the ore is the
reaction of chromite with coke (carbon) to produce
ferrochrome (FeCr_ ).
\begin{equation}
2 \mathrm{C}(\mathrm{s})+\mathrm{FeCr}_{2} \mathrm{O}_{4}(\mathrm{s}) \rightarrow \mathrm{FeCr}_{2}(\mathrm{s})+2 \mathrm{CO}_{2}(\mathrm{g})
\end{equation}
What mole ratio would you use to convert from moles
of chromite to moles of ferrochrome?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 51

Air Pollution The pollutant $\mathrm{SO}_{2}$ is removed from the
air by in a reaction that also involves calcium carbonate
and oxygen. The products of this reaction are calcium
sulfate and carbon dioxide. Determine the mole ratio you
would use to convert moles of $\mathrm{SO}_{2}$ to moles of CaSO..

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 52

Two substances, $\mathrm{W}$ and $\mathrm{X},$ react to form the products $\mathrm{Y}$
and $\mathrm{Z}$ . Table 11.2 shows the moles of the reactants and
products involved when the reaction was carried out.
Use the data to determine the coefficients that will bal-
ance the equation $\mathrm{W}+\mathrm{X} \rightarrow \mathrm{Y}+\mathrm{Z}$

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 53

Antacids Magnesium hydroxide is an ingredient in
some antacids. Antacids react with excess hydrochloric
acid in the stomach to relieve indigestion.
\begin{equation}
\underline\ \mathrm{Mg}(\mathrm{OH})_{2}+\longrightarrow \mathrm{HCl} \rightarrow \underline{} \mathrm{MgCl}_{2}+\underline{} \mathrm{H}_{2} \mathrm{O}
\end{equation}
\begin{equation}
\begin{array}{l}{\text { a. Balance the reaction of Mg }(\mathrm{OH})_{2} \text { with HCl. }} \\ {\text { b. Write the mole ratio that would be used to determine }} \\ {\text { the number of moles of MgCl produced when HCl }} \\ {\text { reacts with } \mathrm{Mg}(\mathrm{OH})_{2} \text { . }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 54

What is the first step in all stoichiometric calculations?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 55

What information does a balanced equation provide?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 56

On what law is stoichometry based, and how do the
calculations support this law?

David Alvarez-Carbonell

David Alvarez-Carbonell

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Problem 57

How is molar mass used in some stoichiometric
calculations?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 58

What information must you have in order to calculate
the mass of product formed in a chemical reaction?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 59

Each box in Figure 11.11 represents the contents of a
flask. One flask contains hydrogen sulfide, and the other
contains oxygen. When the contents of the flasks are mixed, a reaction occurs and water vapor and sulfur are produced. In the figure, the red circles represent oxygen,
the yellow circles represent sulfur, and blue circles represent hydrogen.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the reaction. }} \\ {\text { b. Using the same color code, sketch a representation of }} \\ {\text { the flask after the reaction occurs. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 60

Ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right),$ also known as grain alcohol, can
be made from the fermentation of sugar $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right) .$The unbalanced chemical equation for the reaction is shown below.
\begin{equation}
-\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \rightarrow_{-} \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+_{-} \mathrm{CO}_{2}
\end{equation}
\begin{equation}
\begin{array}{l}{\text { Balance the chemical equation and determine the mass }} \\ {\text { of } \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \text { produced from } 750 \mathrm{g} \text { of } \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \text { . }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 61

Welding If 5.50 mol of calcium carbide $\left(\mathrm{CaC}_{2}\right)$ reacts
with an excess of water, how many moles of acetylene
$\left(\mathrm{C}_{2} \mathrm{H}_{2}\right),$ a gas used in welding, will be produced?
\begin{equation}
\mathrm{CaC}_{2}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{g})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 62

Antacid Fizz When an antacid tablet dissolves in water,
the fizz is due to a reaction between sodium hydrogen
carbonate $\left(\mathrm{NaHCO}_{3}\right),$ also called sodium bicarbonate,
and citric acid $\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right)$
\begin{equation}
3 \mathrm{NaHCO}_{3}(\mathrm{aq})+\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq}) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad3 \mathrm{CO}_{2}(\mathrm{g})+3 \mathrm{H}_{2} \mathrm{O}(1)+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})\end{equation}
How many moles of $\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}$ can be produced if one
tablet containing 0.0119 $\mathrm{mol}$ of $\mathrm{NaHCO}_{3}$ is dissolved?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 63

Esterification The process in which an organic acid
and an alcohol react to form an ester and water is known
as esterification. Ethyl butanoate $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOC}_{2} \mathrm{H}_{5}\right),$ an ester, is formed when the alcohol ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$
and butanoic acid $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$ and are heated in the presence of sulfuric acid.
\begin{equation}
\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(1)+\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}(1) \rightarrow
\end{equation}
\begin{equation}
\mathrm\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad{C}_{3} \mathrm{H}_{7} \mathrm{COOC}_{2} \mathrm{H}_{5}(1)+\mathrm{H}_{2} \mathrm{O}(1)
\end{equation}
Determine the mass of ethyl butanoate produced if 4.50 mol of ethanol is used.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 64

Greenhouse Gas Carbon dioxide is a greenhouse gas
that is linked to global warming. It is released into the
atmosphere through the combustion of octane $\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)$ in gasoline. Write the balanced chemical equation for
the combustion of octane and calculate the mass of
octane needed to release 5.00 $\mathrm{mol}$ of $\mathrm{CO}_{2} .$

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 65

A solution of potassium chromate reacts with a solution
of lead(II) nitrate to produce a yellow precipitate of
lead(II) chromate and a solution of potassium nitrate.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation. }} \\ {\text { b. Starting with } 0.250 \text { mol of potassium chromate, }} \\ {\text { determine the mass of lead chromate formed. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 66

Rocket Fuel The exothermic reaction between liquid
hydrazine $\left(\mathrm{N}_{2} \mathrm{H}_{2}\right)$ and liquid hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)$
is used to fuel rockets. The products of this reaction are
nitrogen gas and water.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation. }} \\ {\text { b. How much hydrazine, in grams, is needed to produce }} \\ {10.0 \text { mol of nitrogen gas? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 67

Chloroform (CHCl_ $),$ an important solvent, is produced
by a reaction between methane and chlorine.
\begin{equation}
\mathrm{CH}_{4}(\mathrm{g})+3 \mathrm{Cl}_{2}(\mathrm{g}) \rightarrow \mathrm{CHCl}_{3}(\mathrm{g})+3 \mathrm{HCl}(\mathrm{g})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 68

Oxygen Production The Russian Space Agency uses
potassium superoxide $\left(\mathrm{KO}_{2}\right)$ for the chemical oxygen
generators in their space suits.
\begin{equation}
4 \mathrm{KO}_{2}+2 \mathrm{H}_{2} \mathrm{O}+4 \mathrm{CO}_{2} \rightarrow 4 \mathrm{KHCO}_{3}+3 \mathrm{O}_{2}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 69

Gasohol is a mixture of ethanol and gasoline. Balance
the equation, and determine the mass of $\mathrm{CO}_{2}$ produced
from the combustion of 100.0 g of ethanol.
\begin{equation}
\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{l})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 70

Car Battery Car batteries use lead, lead(IV) oxide, and
a sulfuric acid solution to produce an electric current.
The products of the reaction are lead(II) sulfate in solution and water.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced equation for the reaction. }} \\ {\text { b. Determine the mass of lead(II) sulfate produced }} \\ {\text { when } 25.0 \text { g of lead reacts with an excess of lead(IV) }} \\ {\text { oxide and sulfuric acid. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 71

To extract gold from its ore, the ore is treated with sodium
cyanide solution in the presence of oxygen and water.
\begin{equation}
4 \mathrm{Au}(\mathrm{s})+8 \mathrm{NaCN}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(1) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad4 \mathrm{NaAu}(\mathrm{CN})_{2}(\mathrm{aq})+4 \mathrm{NaOH}(\mathrm{aq})
\end{equation}
\begin{equation}
\begin{array}{l}{\text { a. Determine the mass of gold that can be extracted if }} \\ {25.0 \text { g of sodium cyanide is used. }} \\ {\text { b. If the mass of the ore from which the gold was }} \\ {\text { extracted is } 150.0 \mathrm{g}, \text { what percentage of the ore is gold? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 72

Film Photographic film contains silver bromide in gelatin. Once exposed, some of the silver bromide decomposes, producing fine grains of silver. The unexposed
silver bromide is removed by treating the film with
sodium thiosulfate. Soluble sodium silver thiosulfate $\left(\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}\right)$ is produced.
\begin{equation}
\mathrm{AgBr}(\mathrm{s})+2 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq}) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NaBr}(\mathrm{aq})
\end{equation}
Determine the mass of $\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}$ produced if
0.275 $\mathrm{g}$ of $\mathrm{AgBr}$ is removed.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 73

How is a mole ratio used to find the limiting reactant?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 74

Explain why the statement, "The limiting reactant is the
reactant with the lowest mass" is incorrect.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 75

Figure 11.12 uses squares to represent Element $M$ and
circles to represent Element $\mathrm{N}$ .
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced equation for the reaction. }} \\ {\text { b. If each square represents 1 mol of } \mathrm{M} \text { and each circle }} \\ {\text { represents 1 mol of } \mathrm{N} \text { , how many moles of M and } \mathrm{N}} \\ {\text { were present at the start of the reaction? }}\end{array}
\end{equation}
\begin{equation}
\begin{array}{l}{\text { c. How many moles of product form? How many moles }} \\ {\text { of Element } \mathrm{M} \text { and Element } \mathrm{N} \text { are unreacted? }} \\ {\text { d. Identify the limiting reactant and the excess reactant. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 76

The reaction between ethyne $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)$ and hydrogen $\left(\mathrm{H}_{2}\right)$
is illustrated in Figure $11.13 .$ The product is ethane
$\left(\mathrm{C}_{2} \mathrm{H}_{6}\right) .$ Which is the limiting reactant? Which is the
excess reactant? Explain.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 77

Nickel-Iron Battery In 1901 , Thomas Edison invented
the nickel-iron battery. The following reaction takes
place in the battery.
\begin{equation}
\mathrm{Fe}(\mathrm{s})+2 \mathrm{NiO}(\mathrm{OH})(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\mathrm{Fe}(\mathrm{OH})_{2}(\mathrm{s})+2 \mathrm{Ni}(\mathrm{OH})_{2}(\mathrm{aq})
How many mol of $\mathrm{Fe}(\mathrm{OH})_{2}$ is produced when 5.00 $\mathrm{mol}$
of Fe and 8.00 $\mathrm{mol}$ of $\mathrm{NiO}(\mathrm{OH})$ react?
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 78

One of the few xenon compounds that form is cesium
xenon heptafluoride (CsXeF 7$) .$ How many moles of CsXeF_ can be produced from the reaction of 12.5 $\mathrm{mol}$ of cesium fluoride with 10.0 mol of xenon hexafluoride?
\begin{equation}
\mathrm{CsF}(\mathrm{s})+\mathrm{XeF}_{6}(\mathrm{s}) \rightarrow \mathrm{Cs} \mathrm{XeF}_{7}(\mathrm{s})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 79

Iron Production Iron is obtained commercially by the
reaction of hematite $\left(\mathrm{Fe}_{2} \mathrm{O}_{3}\right)$ with carbon monoxide.
How many grams of iron is produced when 25.0 $\mathrm{mol}$
of hematite reacts with 30.0 $\mathrm{mol}$ of carbon monoxide?
\begin{equation}
\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+3 \mathrm{CO}(\mathrm{g}) \rightarrow 2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_{2}(\mathrm{g})
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 80

The reaction of chlorine gas with solid phosphorus (P $_{4} )$
produces solid phosphorus pentachloride. When 16.0 $\mathrm{g}$
of chlorine reacts with 23.0 $\mathrm{g}$ of $\mathrm{P}_{4},$ which reactant is
limiting? Which reactant is in excess?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 81

Alkaline Battery An alkaline battery produces electrical
energy according to this equation.
\begin{equation}
\mathrm{Zn}(\mathrm{s})+2 \mathrm{MnO}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{Mn}_{2} \mathrm{O}_{3}(\mathrm{s})
\end{equation}
\begin{equation}
\begin{array}{l}{\text { a. Determine the limiting reactant if } 25.0 \mathrm{g} \text { of } \mathrm{Zn} \text { and }} \\ {30.0 \mathrm{g} \text { of } \mathrm{MnO}_{2} \text { are used. }} \\ {\text { b. Determine the mass of } \mathrm{Zn}(\mathrm{OH})_{2} \text { produced. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 82

Lithium reacts spontaneously with bromine to produce
lithium bromide. Write the balanced chemical equation
for the reaction. If 25.0 g of lithium and 25.0 g of bromine
are present at the beginning of the reaction, determine
\begin{equation}
\begin{array}{l}{\text { a. the limiting reactant. }} \\ {\text { b. the mass of lithium bromide produced. }} \\ {\text { c. the excess reactant and the excess mass. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 83

What is the difference between actual yield and theoretical yield?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 84

How are actual yield and theoretical yield determined?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 85

Can the percent yield of a chemical reaction be more
than 100$\% ?$ Explain your answer.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 86

What relationship is used to determine the percent yield
of a chemical reaction?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 87

What experimental information do you need in order to
calculate both the theoretical and the percent yield of
any chemical reaction?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 88

A metal oxide reacts with water to produce a metal
hydroxide. What additional information would you
need to determine the percent yield of metal hydroxide
from this reaction?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 89

Examine the reaction represented in Figure $11.14 .$
Determine if the reaction went to completion. Explain
your answer, and calculate the percent yield of the
reaction.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 90

Ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is produced from the fermentation
of sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ in the presence of enzymes.
$\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightarrow 4 \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(1)+4 \mathrm{CO}_{2}(\mathrm{g})$ Determine the theoretical yield and the percent yield of
ethanol if 684 $\mathrm{g}$ of sucrose undergoes fermentation and
349 $\mathrm{g}$ of ethanol is obtained.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 91

Lead(II) oxide is obtained by roasting galena, lead(II) sulfide, in air. The unbalanced equation is:
\begin{equation}
\mathrm{PbS}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{PbO}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g})
\end{equation}
\begin{equation}
\begin{array}{l}{\text { a. Balance the equation, and determine the theoretical }} \\ {\text { yield of } \mathrm{PbO} \text { if } 200.0 \mathrm{g} \text { of } \mathrm{PbS} \text { is heated. }} \\ {\text { b. What is the percent yield if } 170.0 \mathrm{g} \text { of } \mathrm{PbO} \text { is obtained? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 92

Upon heating, calcium carbonate $\left(\mathrm{CaCO}_{3}\right)$ decomposes to calcium oxide $(\mathrm{CaO})$ and carbon dioxide $\left(\mathrm{CO}_{2}\right)$
\begin{equation}
\begin{array}{l}{\text { a. Determine the theoretical yield of } \mathrm{CO}_{2} \text { if } 235.0 \mathrm{g} \text { of }} \\ {\mathrm{CaCO}_{3} \text { is heated. }}\end{array}
\end{equation}
\begin{equation}
\begin{array}{l}{\text { b. What is the percent yield of } \mathrm{CO}_{2} \text { if } 97.5 \mathrm{g} \text { of } \mathrm{CO}_{2} \text { is }} \\ {\text { collected? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 93

Hydrofluoric acid solutions cannot be stored in glass
containers because HF reacts readily with silica dioxide
in glass to produce hexafluorosilicic acid $\left(\mathrm{H}_{2} \mathrm{SiF}_{6}\right)$
\begin{equation}
\mathrm{SiO}_{2}(\mathrm{s})+6 \mathrm{HF}(\mathrm{aq}) \rightarrow \mathrm{H}_{2} \mathrm{SiF}_{6}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(1)
\end{equation}
40.0 $\mathrm{g} \mathrm{SiO}_{2}$ and 40.0 $\mathrm{g}$ HF react to yield 45.8 $\mathrm{g} \mathrm{H}_{2} \mathrm{SiF}_{6}$
\begin{equation}
\begin{array}{l}{\text { a. What is the limiting reactant? }} \\ {\text { b. What is the mass of the excess reactant? }}\end{array}
\end{equation}
\begin{equation}
\begin{array}{l}{\text { c. What is the theoretical yield of } \mathrm{H}_{2} \mathrm{SiF}_{6} \text { ? }} \\ {\text { d. What is the percent yield? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 94

Van Arkel Process Pure zirconium is obtained using
the two-step Van Arkel process. In the first step, impure
zirconium and iodine are heated to produce zirconium
iodide $\left(Z r I_{4}\right) .$ In the second step, ZrI $_{4}$ is decomposed to
produce pure zirconium.
\begin{equation}
\mathrm{ZrI}_{4}(\mathrm{s}) \rightarrow \mathrm{Zr}(\mathrm{s})+2 \mathrm{I}_{2}(\mathrm{g})
\end{equation}
Determine the percent yield of zirconium if 45.0 $\mathrm{g}$ of
$\mathrm{ZrI}_{4}$ is decomposed and 5.00 $\mathrm{g}$ of pure Zr is obtained.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 95

Methanol, wood alcohol, is produced when carbon monoxide reacts with hydrogen gas.
\begin{equation}
\mathrm{CO}+2 \mathrm{H}_{2} \rightarrow \mathrm{CH}_{3} \mathrm{OH}
\end{equation}
When 8.50 g of carbon monoxide reacts with an excess
of hydrogen, 8.52 g of methanol is collected. Complete
Table $11.4,$ and calculate the percent yield.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 96

Phosphorus (P. ) is commercially prepared by heating a mixture of calcium phosphate $\left(\mathrm{Ca} \mathrm{SiO}_{3}\right),$ sand $\left(\mathrm{SiO}_{2}\right)$
and coke $(\mathrm{C})$ in an electric furnace. The process involves
two reactions.
\begin{equation}
2 \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}(\mathrm{s})+6 \mathrm{SiO}_{2}(\mathrm{s}) \rightarrow 6 \mathrm{CaSiO}_{3}(\mathrm{l})+\mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{g})
\end{equation}
\begin{equation}
\mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{g})+10 \mathrm{C}(\mathrm{s}) \rightarrow \mathrm{P}_{4}(\mathrm{g})+10 \mathrm{CO}(\mathrm{g})
\end{equation}
The P $_{4} \mathrm{O}_{10}$ produced in the first reaction reacts with an
excess of coke $(\mathrm{C})$ in the second reaction. Determine
the theoretical yield of $\mathrm{P}_{4}$ if 250.0 $\mathrm{g}$ of $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$ and 400.0 $\mathrm{g}$ of $\mathrm{SiO}_{2}$ are heated. If the actual yield of $\mathrm{P}_{4}$ is
$45.0 \mathrm{g},$ determine the percent yield of $\mathrm{P}_{4} .$

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 97

Chlorine forms from the reaction of hydrochloric acid with manganese(IV) oxide. The balanced equation is:
\begin{equation}
\mathrm{MnO}_{2}+4 \mathrm{HCl} \rightarrow \mathrm{MnCl}_{2}+\mathrm{Cl}_{2}+2 \mathrm{H}_{2} \mathrm{O}
\end{equation}
Calculate the theoretical yield and the percent yield of
chlorine if 86.0 $\mathrm{g}$ of $\mathrm{MnO}_{2}$ and 50.0 $\mathrm{g}$ of $\mathrm{HCl}$ react. The
actual yield of $\mathrm{Cl}_{2}$ is 20.0 $\mathrm{g}$ .

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 98

Ammonium sulfide reacts with copper(II) nitrate in a double replacement reaction. What mole ratio would you use to determine the moles of $\mathrm{NH}_{4} \mathrm{NO}_{3}$ produced if the moles of CuS are known?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 99

Fertilizer The compound calcium cyanamide $($ CaNCN) is used as a nitrogen source for crops. To obtain this compound, calcium carbide is reacted with nitrogen at high temperatures.
\begin{equation}
\mathrm{CaC}_{2}(\mathrm{s})+\mathrm{N}_{2}(\mathrm{g}) \rightarrow \mathrm{CaNCN}(\mathrm{s})+\mathrm{C}(\mathrm{s})
\end{equation}
What mass of CaNCN can be produced if 7.50 mol of
CaC $_{2}$ reacts with 5.00 mol of $N_{2} ?$

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 100

When copper(II) oxide is heated in the presence of
hydrogen gas, elemental copper and water are produced.
What mass of copper can be obtained if 32.0 $\mathrm{g}$ of
copper(II) oxide is used?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 101

Air Pollution Nitrogen oxide, which is present in urban air pollution, immediately converts to nitrogen
dioxide as it reacts with oxygen.
\begin{equation}
\begin{array}{l}{\text { a. Write the balanced chemical equation for the forma- }} \\ {\text { tion of nitrogen dioxide from nitrogen oxide. }} \\ {\text { b. What mole ratio would you use to convert from }} \\ {\text { moles of nitrogen oxide to moles of nitrogen dioxide? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 102

Electrolysis Determine the theoretical and percent
yield of hydrogen gas if 36.0 g of water undergoes electrolysis to produce hydrogen and oxygen and 3.80 g of hydrogen is collected.

Chareen Guzman

Numerade Educator

Problem 103

Iron reacts with oxygen as shown.
\begin{equation}
4 \mathrm{Fe}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})
\end{equation}
Different amounts of iron were burned in a fixed
amount of oxygen. For each mass of iron burned, the
mass of iron(II) oxide formed was plotted on the graph shown in Figure $11.15 .$ Why does the graph level off
after 25.0 g of iron is burned? How many moles of
oxygen are present in the fixed amount?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 104

Analyze and Conclude In an experiment, you obtain a
percent yield of product of 108$\% .$ Is such a percent yield
possible? Explain. Assuming that your calculation is
correct, what reasons might explain such a result?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 105

Observe and Infer Determine whether each reaction
depends on a limiting reactant. Explain why or why not,
and identify the limiting reactant.
\begin{equation}
\begin{array}{l}{\text { a. Potassium chlorate decomposes to form potassium }} \\ {\text { chloride and oxygen. }} \\ {\text { b. Silver nitrate and hydrochloric acid react to produce }} \\ {\text { silver chloride and nitric acid. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 106

Design an Experiment Design an experiment that can
be used to determine the percent yield of anhydrous
copper(II) sulfate when copper(II) sulfate pentahydrate
is heated to remove water.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 107

Apply When a campfire begins to die down and
smolder, you can rekindle the flame by fanning the fire.
Explain, in terms of stoichiometry, why the fire again
begins to flare up when fanned.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 108

Apply Students conducted a lab to investigate limiting
and excess reactants. The students added different
volumes of sodium phosphate solution $\left(\mathrm{Na}_{3} \mathrm{PO}_{4}\right)$ to a
beaker. They then added a constant volume of cobalt(II) nitrate solution $\left(\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}\right),$ stirred the contents, and
allowed the beakers to sit overnight. The next day, each
beaker had a purple precipitate at the bottom. The students decanted the supernatant from each beaker, divided it into two samples, and added one drop of sodium
phosphate solution to one sample and one drop of
cobalt(II) nitrate solution to the second sample. Their
results are shown in Table $11.5 .$
\begin{equation}
\begin{array}{l}{\text { a. Write a balanced chemical equation for the reaction. }} \\ {\text { b. Based on the results, identify the limiting reactant }} \\ {\text { and the excess reactant for each trial. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 109

When 9.59 g of a certain vanadium oxide is heated in
the presence of hydrogen, water and a new oxide of
vanadium are formed. This new vanadium oxide has a
mass of 8.76 g. When the second vanadium oxide undergoes additional heating in the presence of hydrogen, 5.38 g of vanadium metal forms.
\begin{equation}
\begin{array}{l}{\text { a. Determine the empirical formulas for the two }} \\ {\text { vanadium oxides. }} \\ {\text { b. Write balanced equations for the steps of the reaction. }} \\ {\text { c. Determine the mass of hydrogen needed to complete }} \\ {\text { the steps of this reaction. }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 110

You observe that sugar dissolves more quickly in hot tea
than in iced tea. You state that higher temperatures
increase the rate at which sugar dissolves in water. Is this
statement a hypothesis or a theory? Why? (Chapter 1)

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 111

Write the electron configuration for each of the following atoms. (Chapter 5)
\begin{equation}
\begin{array}{ll}{\text { a. fluorine }} & {\text { c. titanium }} \\ {\text { b. aluminum }} & {\text { d. radon }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 112

Explain why the gaseous nonmetals exist as diatomic
molecules, but other gaseous elements exist as single
atoms. (Chapter 8)

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 113

Write a balanced equation for the reaction of potassium
with oxygen. (Chapter 9)

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 114

What is the molecular mass of $\mathrm{UF}_{6} ?$ What is the molar mass of $\mathrm{UF}_{6}?$ (Chapter 10)

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 115

Figure 11.16 gives percent composition data for several organic compounds. (Chapter 10$)$
\begin{equation}
\begin{array}{l}{\text { a. How are the molecular and empirical formulas of }} \\ {\text { acetaldehyde and butanoic acid related? }} \\ {\text { b. What is the empirical formula of butanoic acid? }}\end{array}
\end{equation}

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 116

Air Pollution Research the air pollutants produced
by combustion of gasoline in internal combustion
engines. Discuss the common pollutants and the
reaction that produces them. Show, through the use
of stoichiometry, how each pollutant could be
reduced if more people used mass transit.

James Irizarry

Numerade Educator

Problem 117

Haber Process The percent yield of ammonia produced when hydrogen and nitrogen are combined
under ordinary conditions is extremely small.
However, the Haber Process combines the two gases under a set of conditions designed to maximize yield. Research the conditions used in the Haber Process, and find out why the development of the process was of great importance.

Ronald Prasad

Numerade Educator

Problem 118

Balance the equation in Figure $11.17 .$ If the
bombardier beetle stores 100.0 $\mathrm{mg}$ of hydroquinone
$\left(\mathrm{C}_{6} \mathrm{H}_{4}(\mathrm{OH})_{2}\right)$ along with 50.0 $\mathrm{mg}$ of hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right),$ what is the limiting reactant?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 119

What is the excess reactant and how many milligrams
are in excess?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 120

How many milligrams of benzoquinone will be
produced?

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator