Chemistry Principles and Practice

Daniel L. Reger, Scott R. Goode, David W. Ball

Chapter 3

Equations, the Mole, and Chemical Formulas - all with Video Answers

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Chapter Questions

Problem 1

What is the difference between writing the names of the reactants and products of the reaction, and writing the chemical equation?

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Problem 2

Describe the steps needed to write balanced equations.

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Problem 3

Using solid circles for $\mathrm{H}$ atoms and open circles for $\mathrm{O}$ atoms, make a drawing that shows the molecular level representation for the balanced equation of $\mathrm{H}_{2}$ and $\mathrm{O}_{2}$ reacting to form $\mathrm{H}_{2} \mathrm{O}$.

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Problem 4

Using solid circles for $\mathrm{H}$ atoms and open circles for $\mathrm{O}$ atoms, make a drawing that shows the molecular level representation for the balanced equation of $\mathrm{H}_{2}$ and $\mathrm{O}_{2}$ reacting to form $\mathrm{H}_{2} \mathrm{O}_{2}$. The two oxygen atoms are bonded to each other, and a hydrogen atom is bonded to each oxygen.

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Problem 5

Give the name and definition of the SI unit for amount of substance.

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Problem 6

How many objects are in 1 mol? What is the common name for this number of objects?

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Problem 7

When writing and balancing a chemical equation, we generally count the number of molecules that are present, but when carrying out reactions in the laboratory, we think of the equation in terms of moles. Why is the unit of moles more convenient on the laboratory scale?

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Problem 8

What are the units for molecular mass, formula mass, and molar mass?

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Problem 9

Draw a diagram that outlines the conversion of number of atoms into moles.

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Problem 10

Draw a flow diagram that outlines the conversion of moles to number of atoms.

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Problem 11

Describe an experiment that would enable someone to determine the percentages of carbon and hydrogen in a sample of a newly prepared hydrocarbon.

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Problem 12

Explain how a combustion analysis is used to determine the percentage of oxygen in a new compound that contains only carbon, hydrogen, and oxygen.

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Problem 13

Only the empirical formula can be calculated from percentage composition data. What additional information is needed to calculate the molecular formula from the empirical formula, and if given this information, how is the molecular formula determined?

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Problem 14

Interpret the following equation in terms of number of moles.
$$
\mathrm{N}_{2}+2 \mathrm{H}_{2} \rightarrow \mathrm{N}_{2} \mathrm{H}_{4}
$$

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Problem 15

Draw a flow diagram used to answer the following question, "How many grams of $\mathrm{N}_{2}$ are needed to exactly react with $2.44 \mathrm{~g} \mathrm{H}_{2}$ given the equation $\mathrm{N}_{2}+2 \mathrm{H}_{2} \rightarrow \mathrm{N}_{2} \mathrm{H}_{4}$ ?"

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Problem 16

Describe what is meant by the expression, "The reaction was carried out with the reactants present in stoichiometric amounts."

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Problem 17

Describe a method of determining the limiting reactant in a calculation based on the individual masses of each of the
reactants.

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Problem 18

Describe what is meant by the statement, "In a combustion reaction, $\mathrm{C}_{2} \mathrm{H}_{4}$ is the limiting reactant and oxygen is present in excess."

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Problem 19

A mixture of carbon monoxide and oxygen gas reacts as shown below.
(a) Write the balanced equation (remember to express the coefficients as the lowest set of whole numbers).
(b) Name the product.

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Problem 20

A mixture of sulfur dioxide and oxygen gas reacts as shown below.
(a) Write the balanced equation (remember to express the coefficients as the lowest set of whole numbers).
(b) Name the product.

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Problem 21

Write balanced equations for the following reactions.
(a) $\mathrm{C}_{5} \mathrm{H}_{12}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}$
(b) $\mathrm{NH}_{3}+\mathrm{O}_{2} \rightarrow \mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}$
(c) $\mathrm{KOH}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{K}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}$

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Problem 22

Write balanced equations for the following reactions.
(a) $\mathrm{Mg}_{3} \mathrm{~N}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{3}+\mathrm{Mg}(\mathrm{OH})_{2}$
(b) $\mathrm{Fe}+\mathrm{O}_{2} \rightarrow \mathrm{Fe}_{2} \mathrm{O}_{3}$

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Problem 23

Write balanced equations for the following reactions.
(a) $\mathrm{N}_{2} \mathrm{H}_{4}+\mathrm{N}_{2} \mathrm{O}_{4} \rightarrow \mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}$
(b) $\mathrm{F}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{HF}+\mathrm{O}_{2}$
(c) $\mathrm{Na}_{2} \mathrm{O}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NaOH}$

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Problem 24

Balance these reactions.
(a) $\mathrm{Al}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})$
(b) $\mathrm{N}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{NH}_{3}(\mathrm{~g})$
(c) $\mathrm{C}_{6} \mathrm{H}_{6}(\ell)+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CO}_{2}(\mathrm{~g})$

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Problem 25

(a) Write the equation for perchloric acid $\left(\mathrm{HClO}_{4}\right)$ dissolving in water.
(b) Write the equation for sodium nitrate dissolving in water.

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Problem 26

(a) Write the equation for hydrofluoric acid (HF) dissolving in water.
(b) Write the equation for lithium sulfate dissolving in water.

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Problem 27

(a) Write the equation for nitric acid $\left(\mathrm{HNO}_{3}\right)$ dissolving in water.
(b) Write the equation for potassium carbonate dissolving in water.

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Problem 28

(a) Write the equation for hydrochloric acid dissolving in water.
(b) Write the equation for barium nitrate dissolving in water.

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Problem 29

Write a balanced equation for the reaction of
(a) $\mathrm{NaOH}$ and $\mathrm{H}_{2} \mathrm{SO}_{4}$.
(b) calcium hydroxide and $\mathrm{HCl}$.
(c) $\mathrm{HNO}_{3}$ and lithium hydroxide.

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Problem 30

Write a balanced equation for the reaction of
(a) $\mathrm{Mg}(\mathrm{OH})_{2}$ and $\mathrm{HF}$.
(b) sodium hydroxide and HCl.
(c) $\mathrm{H}_{2} \mathrm{SO}_{4}$ and strontium hydroxide.

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Problem 31

Write a balanced equation for the combustion (in excess oxygen) of each of the following compounds.
(a) $\mathrm{C}_{6} \mathrm{H}_{12}$
(b) $\mathrm{C}_{4} \mathrm{H}_{8}$
(c) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$
(d) $\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{2}$

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Problem 32

Write a balanced equation for each of these combustion reactions.
(a) $\mathrm{C}_{4} \mathrm{H}_{10}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow$
(b) $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{~s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow$
(c) $\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}(\ell)+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow$

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Problem 33

Write a balanced equation for
(a) the combustion of $\mathrm{C}_{6} \mathrm{H}_{10}$ and $\mathrm{O}_{2}$.
(b) the reaction of $\mathrm{Be}(\mathrm{OH})_{2}$ and nitric acid.

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Problem 34

Write a balanced equation for
(a) the combustion of $\mathrm{C}_{8} \mathrm{H}_{8}$ and $\mathrm{O}_{2}$.
(b) the reaction of potassium hydroxide and $\mathrm{HCl}$.

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Problem 35

The reaction of carbon disulfide and oxygen yields sulfur dioxide and carbon dioxide. Write the balanced equation for this reaction.

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Problem 36

Methyl tertiarybutyl ether, $\mathrm{CH}_{3} \mathrm{OC}\left(\mathrm{CH}_{3}\right)_{3}, \mathrm{MTBE},$ is a compound that is added to gasoline to increase the octane rating, replacing the toxic compound tetraethyl lead that was used previously. Unfortunately, methyl tertiarybutyl ether has contaminated groundwater in certain locations and is being phased out. Write the equation for the combustion of MTBE in excess oxygen.

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Problem 37

Acetone, $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO},$ is an important industrial compound. Although its toxicity is relatively low, workers using it must be careful to avoid flames and sparks because this compound burns readily in air. Write the balanced equation for the combustion of acetone.

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Problem 38

The substance $\mathrm{H}_{3} \mathrm{PO}_{3}$ can be converted into $\mathrm{H}_{3} \mathrm{PO}_{4}$ and $\mathrm{PH}_{3}$ by heating. Write the balanced equation for this reaction.

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Problem 39

Disulfur dichloride is used to vulcanize rubber. It is prepared by the reaction of elemental sulfur, $\mathrm{S}_{8}$, and chlorine gas, $\mathrm{Cl}_{2}$. Write the balanced equation for this reaction.

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Problem 40

Uranium dioxide reacts with carbon tetrachloride vapor at high temperatures, forming green crystals of uranium tetrachloride and phosgene, $\mathrm{COCl}_{2}$, a poisonous gas. Write the balanced equation for this reaction.

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Problem 41

Identify the oxidation numbers of the atoms in the following substances.
(a) $\mathrm{N}_{2}$
(b) $\mathrm{NaBr}$
(c) $\mathrm{Na}_{2} \mathrm{SO}_{4}$
(d) $\mathrm{HNO}_{3}$
(e) $\mathrm{PCl}_{5}$
(f) $\mathrm{CH}_{2} \mathrm{O}$

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Problem 42

Identify the oxidation numbers of the atoms in the following substances.
(a) $\mathrm{NH}_{4} \mathrm{Cl}$
(b) $\mathrm{N}_{2} \mathrm{O}$
(c) $\mathrm{Ag}$
(d) $\mathrm{AuI}_{3}$

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Problem 43

In the ionic compound sodium hydride, $\mathrm{NaH},$ the hydrogen atom does not have its common oxidation number. On the basis of the formula of this compound, what is the oxidation number of the $\mathrm{H}$ atom?

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Problem 44

In compounds called peroxides, the oxygen atoms do not have oxidation numbers common for oxygen atoms. On the basis of the formula of sodium peroxide, $\mathrm{Na}_{2} \mathrm{O}_{2}$, what is the oxidation number of the $\mathrm{O}$ atoms?

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Problem 45

A The reaction of hydrazine, $\mathrm{N}_{2} \mathrm{H}_{4}$, with molecular oxygen is violent because it rapidly produces large quantities of gases and heat. For this reason, hydrazine has been used as a rocket fuel. The products of the reaction are $\mathrm{NO}_{2}$ and water. Write the balanced equation for this reaction. Assign oxidation numbers to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 46

The reaction of iron metal with oxygen gas at increased temperatures yields iron(III) oxide. Write the balanced equation for this reaction. Assign an oxidation number to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 47

Zinc metal and HCl react to yield zinc(II) chloride and hydrogen gas. Write the balanced equation for this reaction. Assign oxidation numbers to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 48

White phosphorus, $\mathrm{P}_{4}$, is a solid at room temperature. It reacts with molecular oxygen to yield solid $\mathrm{P}_{4} \mathrm{O}_{10} .$ Write the balanced equation for this reaction, including the physical states. Assign an oxidation number to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 49

One of the ways to remove nitrogen monoxide gas, a serious source of air pollution, from smokestack emissions is by reaction with ammonia gas, $\mathrm{NH}_{3}$. The products of the reaction, $\mathrm{N}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$, are not toxic. Write the balanced equation for this reaction. Assign an oxidation number to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 50

The reaction of $\mathrm{MnO}_{2}$ and $\mathrm{HCl}$ yields $\mathrm{MnCl}_{2}, \mathrm{Cl}_{2}$, and water. Write the balanced equation for this reaction. Assign an oxidation number to each element in the reactants and products, and indicate which element is oxidized and which is reduced.

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Problem 51

State how many atoms are present in the following samples.
(a) $1.44 \mathrm{~mol} \mathrm{Mg}$
(b) $9.77 \mathrm{~mol} \mathrm{Ne}$
(c) $0.099 \mathrm{~mol} \mathrm{Fe}$

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Problem 52

State how many atoms are present in the following samples.
(a) $0.0778 \mathrm{~mol} \mathrm{Xe}$
(b) $1.45 \mathrm{~mol} \mathrm{~K}$
(c) $55.8 \mathrm{~mol} \mathrm{Ti}$

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Problem 53

State how many molecules are present in the following samples.
(a) $99.2 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}$
(b) $1.22 \mathrm{~mol} \mathrm{~N}_{2}$
(c) $22.9 \mathrm{~mol} \mathrm{C}_{3} \mathrm{H}_{6}$
(d) $0.0022 \mathrm{~mol} \mathrm{~N}_{2} \mathrm{O}$

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Problem 54

State how many molecules are present in the following samples.
(a) $0.223 \mathrm{~mol} \mathrm{Cl}_{2}$
(b) $14.7 \mathrm{~mol} \mathrm{~N}_{2} \mathrm{H}_{4}$
(c) $0.334 \mathrm{~mol} \mathrm{C}_{9} \mathrm{H}_{18}$
(d) $1.22 \mathrm{~mol} \mathrm{CO}_{2}$

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Problem 55

State how many moles are present in the following samples.
(a) $3.44 \times 10^{24}$ molecules of $\mathrm{O}_{2}$
(b) $1.11 \times 10^{22}$ atoms of $\mathrm{Na}$
(c) $5.57 \times 10^{30}$ molecules of $\mathrm{C}_{2} \mathrm{H}_{6}$
(d) $1.66 \times 10^{24}$ molecules of $\mathrm{CO}$

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Problem 56

State how many moles are present in the following samples.
(a) $1.33 \times 10^{26}$ molecules of $\mathrm{Br}_{2}$
(b) $7.71 \times 10^{26}$ molecules of $\mathrm{C}_{5} \mathrm{H}_{12}$
(c) $2.34 \times 10^{23}$ molecules of $\mathrm{B}_{2} \mathrm{H}_{6}$
(d) $7.76 \times 10^{23}$ atoms of Ne

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Problem 57

Give the molar mass of the following substances.
(a) $\mathrm{Na} \mathrm{OH}$
(b) $\mathrm{C}_{2} \mathrm{H}_{4}$
(c) $\mathrm{Mg}(\mathrm{OH})_{2}$

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Problem 58

Give the molar mass of the following substances.
(a) $\mathrm{N}_{2} \mathrm{O}_{4}$
(b) $\mathrm{Na}_{2} \mathrm{SO}_{4}$
(c) $\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O}_{2}$

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Problem 59

Give the molar mass of the following substances.
(a) $\mathrm{ZnBr}_{2}$
(b) $\mathrm{K}_{2} \mathrm{CrO}_{4}$
(c) $\mathrm{BaS}$

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Problem 60

Give the molar mass of the following substances.
(a) $\mathrm{N}_{2} \mathrm{O}_{2}$
(b) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}$
(c) $\mathrm{C}_{8} \mathrm{H}_{15} \mathrm{~N}$

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Problem 61

(a) Calculate the number of moles in $9.40 \mathrm{~g} \mathrm{SO}_{2}$.
(b) Calculate the mass in $3.30 \mathrm{~mol} \mathrm{AlCl}_{3}$.
(c) Calculate the number of moles in $1.12 \times 10^{23}$ molecules of $\mathrm{H}_{2} \mathrm{SO}_{4}$

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Problem 62

How many moles of compound are in
(a) $39.2 \mathrm{~g} \mathrm{H}_{2} \mathrm{SO}_{4} ?$
(b) $8.00 \mathrm{~g} \mathrm{O}_{2}$ ?
(c) $10.7 \mathrm{~g} \mathrm{NH}_{3}$ ?

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Problem 63

(a) Calculate the number of moles in $14.3 \mathrm{~g} \mathrm{C}_{6} \mathrm{H}_{6}$
(b) Calculate the mass of $0.0535 \mathrm{~mol} \mathrm{SiH}_{4}$.
(c) Calculate the number of molecules in $1.11 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$.

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Problem 64

Calculate the number of moles in the following samples.
(a) $2.2 \mathrm{~g} \mathrm{~K}_{2} \mathrm{SO}_{4}$
(b) $6.4 \mathrm{~g} \mathrm{C}_{8} \mathrm{H}_{12} \mathrm{~N}_{4}$
(c) $7.13 \mathrm{~g} \mathrm{Fe}\left(\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}$

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Problem 65

Calculate the number of moles in the following samples.
(a) $2.2 \mathrm{~g} \mathrm{~K}_{2} \mathrm{SO}_{4}$
(b) $6.4 \mathrm{~g} \mathrm{C}_{8} \mathrm{H}_{12} \mathrm{~N}_{4}$
(c) $7.13 \mathrm{~g} \mathrm{Fe}\left(\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2}$

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Problem 66

Calculate the mass, in grams, of the following samples.
(a) $7.55 \mathrm{~mol} \mathrm{~N}_{2} \mathrm{O}_{4}$
(b) $9.2 \mathrm{~mol} \mathrm{CaCl}_{2}$
(c) $0.44 \mathrm{~mol} \mathrm{CO}$

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Problem 67

(a) Calculate the number of moles in $48.0 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}_{2}$.
(b) Calculate the number of oxygen atoms in this sample.

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Problem 68

(a) Calculate the number of molecules in $3.4 \mathrm{~g} \mathrm{H}_{2}$.
(b) Calculate the number of hydrogen atoms in this sample.

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Problem 69

(a) Calculate the mass, in grams, of $3.50 \mathrm{~mol} \mathrm{NO}_{2}$.
(b) Calculate the number of molecules in this sample.
(c) Calculate the number of nitrogen and oxygen atoms in the sample.

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Problem 70

(a) Calculate the number of moles in $33.1 \mathrm{~g} \mathrm{SO}_{3}$.
(b) Calculate the number of molecules in this sample.
(c) Calculate the number of sulfur and oxygen atoms in the sample.

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Problem 71

Possession of $5.0 \mathrm{~g}$ "crack" cocaine, $\mathrm{C}_{17} \mathrm{H}_{21} \mathrm{NO}_{4}$, is a felony in most states, the conviction of which carries mandatory jail time. How many moles of cocaine is this quantity?

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Problem 72

A standard serving of alcohol is 0.9 fluid ounce pure ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$. If there is $29.56 \mathrm{~mL}$ in one fluid ounce and the density of ethanol is $0.7894 \mathrm{~g} / \mathrm{mL}$, how many moles of ethanol are in a standard serving?

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Problem 73

Colchicine, $\mathrm{C}_{22} \mathrm{H}_{25} \mathrm{NO}_{6}$, is a naturally occurring compound that has been used as a medicine since the time of the pharaohs in ancient Egypt. Although the reasons for its effectiveness are not yet clearly understood, it is still used to treat the inflammation in joints caused by a gout attack.
(a) What is the molar mass of colchicine?
(b) What is the mass, in grams, of $3.2 \times 10^{22}$ molecules of colchicine?
(c) How many moles of colchicine are in a 326 -g sample?
(d) How many carbon atoms are present in 50 molecules of colchicine?

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Problem 74

Nickel tetracarbonyl, $\mathrm{Ni}(\mathrm{CO})_{4},$ is a volatile (easily converted to the gas phase), extremely toxic compound that forms when carbon monoxide gas is passed over finely divided nickel. Despite this toxicity, it has been used for more than a century in a method of making highly purified nickel.
(a) What is the mass of $1.00 \mathrm{~mol} \mathrm{Ni}(\mathrm{CO})_{4}$ ?
(b) How many moles of $\mathrm{Ni}(\mathrm{CO})_{4}$ are in a $3.22-\mathrm{g}$ sample?
(c) How many molecules of $\mathrm{Ni}(\mathrm{CO})_{4}$ are in a $5.67-\mathrm{g}$ sample?
(d) How many atoms of carbon are present in $34 \mathrm{~g}$ $\mathrm{Ni}(\mathrm{CO})_{4} ?$

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Problem 75

A molecular model of methyl alcohol is shown below; the OH group is an alcohol functional group, a group present in many important chemicals. Write the formula of methyl alcohol and use it to calculate the number of moles of hydrogen atoms in $0.33 \mathrm{~mol}$ methyl alcohol.

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Problem 76

A molecular model of hydrogen peroxide is shown below. Write the formula of hydrogen peroxide and use it to calculate the number of moles of hydrogen atoms in 0.011 mol hydrogen peroxide.

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Problem 77

What is the percentage, by mass, of each element in the following substances?
(a) $\mathrm{C}_{4} \mathrm{H}_{8}$
(b) $\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{~N}_{2}$
(c) $\mathrm{Fe}_{2} \mathrm{O}_{3}$

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Problem 78

What is the percentage, by mass, of each element in the following substances?
(a) $\mathrm{C}_{6} \mathrm{H}_{12}$
(b) $\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}$
(c) $\mathrm{NiCl}_{2}$

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Problem 79

What is the mass percentage of each element in acetone, $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O} ?$

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Problem 80

Calculate the mass percentage of copper in CuS, copper(II) sulfide.

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Problem 81

Calculate the mass percentage of copper in $\mathrm{CuS}$, copper(II) sulfide.

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Problem 82

What is the mass percentage of each element in magnesium carbonate?

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Problem 83

The compound sodium borohydride, $\mathrm{NaBH}_{4},$ is used in the preparation of many organic compounds.
(a) What is the molar mass of sodium borohydride?
(b) What is the mass percentage of each element in this compound?

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Problem 84

Calcium carbonate is popular as an antacid because, in addition to neutralizing stomach acid, it provides calcium, a necessary mineral to the body.
(a) What is the formula mass of calcium carbonate?
(b) What is the mass percentage of each element in this compound?

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Problem 85

A chemist prepared a compound that she thought had the formula $\mathrm{FeI}_{3}$. When the compound was analyzed, it contained $18.0 \% \mathrm{Fe}$ and $82.0 \% \mathrm{I} .$ Calculate the mass percentage composition expected for $\mathrm{FeI}_{3}$ and compare the result with that found in the analysis. Is this the correct formula of the compound?

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Numerade Educator

Problem 86

A compound was prepared and analyzed. It was $56.0 \% \mathrm{C}$, $3.92 \% \mathrm{H},$ and $27.6 \% \mathrm{Cl}$ by mass. The compound was thought to have the formula $\mathrm{C}_{6} \mathrm{H}_{4}(\mathrm{OH}) \mathrm{Cl} .$ Calculate the mass percentage of each element in this formula. Is the analysis consistent with this formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 87

Calculate the mass of carbon in the following compounds.
(a) $4.9 \mathrm{~g} \mathrm{CO}$
(b) $2.2 \mathrm{~g} \mathrm{C}_{3} \mathrm{H}_{6}$
(c) $9.33 \mathrm{~g} \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 88

Calculate the mass of carbon in the following compounds.
(a) $1.80 \mathrm{~g} \mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}$
(b) $0.00223 \mathrm{~g} \mathrm{Na}_{2} \mathrm{CO}_{3}$
(c) $22.1 \mathrm{~g} \mathrm{C}_{5} \mathrm{H}_{11} \mathrm{~N}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 89

Calculate the mass of carbon in the following compounds.
(a) $4.32 \mathrm{~g} \mathrm{CO}_{2}$
(b) $2.21 \mathrm{~g} \mathrm{C}_{2} \mathrm{H}_{4}$
(c) $0.0443 \mathrm{~g} \mathrm{CS}_{2}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 90

Calculate the mass of hydrogen in the following compounds.
(a) $4.33 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$
(b) $1.22 \mathrm{~g} \mathrm{C}_{2} \mathrm{H}_{2}$
(c) $4.44 \mathrm{~g} \mathrm{~N}_{2} \mathrm{H}_{4}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 91

A $1.070-\mathrm{g}$ sample of a compound containing only carbon, hydrogen, and oxygen burns in excess $\mathrm{O}_{2}$ to produce $1.80 \mathrm{~g} \mathrm{CO}_{2}$ and $1.02 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ Calculate the mass of each
element in the sample and the mass percentage of each element in the compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 92

A $2.770-\mathrm{g}$ sample containing only carbon, hydrogen, and oxygen burns in excess $\mathrm{O}_{2}$ to produce $4.06 \mathrm{~g} \mathrm{CO}_{2}$ and $1.66 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ Calculate the mass of each element in the sample and the mass percentage of each element in the compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 93

A $3.11-\mathrm{g}$ sample containing only carbon, hydrogen, and nitrogen burns in excess $\mathrm{O}_{2}$ to produce $5.06 \mathrm{~g} \mathrm{CO}_{2}$ and $2.07 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ Calculate the mass of each element in the sample and the mass percentage of each element in the compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 94

A $0.513-\mathrm{g}$ sample containing only carbon, hydrogen, and nitrogen burns in excess $\mathrm{O}_{2}$ to produce $1.04 \mathrm{~g} \mathrm{CO}_{2}$ and $0.704 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ Calculate the mass of each element in the sample and the mass percentage of each element in the compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 95

What is the empirical formula of a compound that contains $0.139 \mathrm{~g}$ hydrogen and $0.831 \mathrm{~g}$ carbon?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 96

What is the empirical formula of a substance that contains $0.80 \mathrm{~g}$ carbon and $0.20 \mathrm{~g}$ hydrogen?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 97

A sample contains $0.571 \mathrm{~g}$ carbon, $0.072 \mathrm{~g}$ hydrogen, and $0.333 \mathrm{~g}$ nitrogen. What is the empirical formula of this substance?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 98

A sample contains $0.152 \mathrm{~g}$ nitrogen and $0.348 \mathrm{~g}$ oxygen. What is the empirical formula of this substance?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 99

What is the empirical formula of a substance that contains only iron and chlorine, and is $44.06 \%$ by mass iron?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 100

What is the empirical formula of a substance containing only selenium and chlorine, and is $52.7 \%$ selenium by mass?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 101

A $1.000-\mathrm{g}$ sample of a compound contains $0.252 \mathrm{~g}$ titanium and $0.748 \mathrm{~g}$ chlorine. Determine the empirical formula of this compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 102

A sample is shown to contain $0.173 \mathrm{~g}$ chromium and $0.160 \mathrm{~g}$ oxygen. What is the empirical formula of this substance?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 103

A compound contains only carbon, hydrogen, and oxygen, and is $66.6 \%$ carbon and $11.2 \%$ hydrogen. What is the empirical formula of this substance?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 104

A $1.20-\mathrm{g}$ sample of a compound gave $2.92 \mathrm{~g}$ of $\mathrm{CO}_{2}$ and $1.22 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$ on combustion in oxygen. The compound is known to contain only $\mathrm{C}, \mathrm{H},$ and $\mathrm{O} .$ What is its empirical formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 105

A platinum compound named cisplatin is effective in the treatment of certain types of cancer. Analysis shows that it contains $65.02 \%$ platinum, $2.02 \%$ hydrogen, $9.34 \%$ nitrogen, and $23.63 \%$ chlorine. What is its empirical formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 106

Carvone is an oil isolated from caraway seeds that is used in perfumes and soaps. This compound contains $79.95 \%$ carbon, $9.40 \%$ hydrogen, and $10.65 \%$ oxygen. What is its empirical formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 107

When a $2.074-\mathrm{g}$ sample that contains only carbon, hydrogen, and oxygen burns in excess $\mathrm{O}_{2},$ the products are $3.80 \mathrm{~g} \mathrm{CO}_{2}$ and $1.04 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ What is the empirical
formula of this compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 108

A $0.459-\mathrm{g}$ sample that contains only carbon, hydrogen, and oxygen reacts with an excess of $\mathrm{O}_{2}$ to produce $0.170 \mathrm{~g} \mathrm{CO}_{2}$ and $0.0348 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$. What is the percentage
of $\mathrm{C}$ and $\mathrm{H}$ in the starting material?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 109

A compound contains only $\mathrm{C}, \mathrm{H}, \mathrm{N},$ and $\mathrm{O} .$ Combustion of a $1.48-\mathrm{g}$ sample in excess $\mathrm{O}_{2}$ yields $2.60 \mathrm{~g} \mathrm{CO}_{2}$ and $0.799 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ A separate experiment shows that a $2.43-\mathrm{g}$ sample contains $0.340 \mathrm{~g} \mathrm{~N}$. What is the empirical formula of the compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 110

A compound contains only $\mathrm{C}, \mathrm{H}, \mathrm{N},$ and $\mathrm{O} .$ Combustion of a $2.18-\mathrm{g}$ sample in excess $\mathrm{O}_{2}$ yields $3.94 \mathrm{~g} \mathrm{CO}_{2}$ and $1.89 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ A separate experiment shows that a 1.23-g sample contains $0.235 \mathrm{~g} \mathrm{~N}$. What is the empirical formula of the compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 111

What is the molecular formula of a compound with an empirical formula of $\mathrm{CH}_{2} \mathrm{O}$ and a molar mass of $90 \mathrm{~g} / \mathrm{mol} ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 112

What is the molecular formula of a compound with an empirical formula of $\mathrm{HO}$ and a molar mass of $34 \mathrm{~g} / \mathrm{mol}$ ?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 113

empirical formula of $\mathrm{HO}$ and a molar mass of $34 \mathrm{~g} / \mathrm{mol}$ ? What is the molecular formula of each of the following compounds?
(a) empirical formula of $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$ and molar mass of $132 \mathrm{~g} / \mathrm{mol}$
(b) empirical formula of $\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{NO}_{3}$ and molar mass of $408 \mathrm{~g} / \mathrm{mol}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 114

What is the molecular formula of each of the following compounds?
(a) empirical formula $\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}$ and molar mass of $258 \mathrm{~g} / \mathrm{mol}$
(b) empirical formula $\mathrm{PCl}_{3}$ and molar mass of $137.3 \mathrm{~g} / \mathrm{mol} ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 115

A compound contains $62.0 \%$ carbon, $10.4 \%$ hydrogen, and $27.5 \%$ oxygen by mass, and has a molar mass of $174 \mathrm{~g} / \mathrm{mol}$. What is the molecular formula of the compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 116

Mandelic acid is an organic acid composed of carbon $(63.15 \%)$, hydrogen $(5.30 \%)$, and oxygen $(31.55 \%)$. Its molar mass is $152.14 \mathrm{~g} / \mathrm{mol}$. Determine the empirical and molecular formulas of the acid.

David Alvarez-Carbonell

David Alvarez-Carbonell

Numerade Educator

Problem 117

Acetic acid gives vinegar its sour taste. Analysis of acetic acid shows it is $40.0 \%$ carbon, $6.71 \%$ hydrogen, and $53.3 \%$ oxygen. Its molar mass is $60 \mathrm{~g} / \mathrm{mol}$. What is its molecular formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 118

Fructose, an important sugar, is made up of $40.0 \%$ carbon, $6.71 \%$ hydrogen, and $53.3 \%$ oxygen. Its molar mass is $180 \mathrm{~g} / \mathrm{mol}$. What is its molecular formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 119

(a) Write the equation for the combustion of propylene, $\mathrm{C}_{3} \mathrm{H}_{6}$
(b) Calculate the mass of $\mathrm{CO}_{2}$ produced when $2.45 \mathrm{~g}$ $\mathrm{C}_{3} \mathrm{H}_{6}$ burns in excess oxygen.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 120

(a) Write the equation for the combustion of $\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}$.
(b) Calculate the mass of $\mathrm{O}_{2}$ consumed in the combustion of a $5.33-\mathrm{g}$ sample of $\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 121

The reaction of $\mathrm{P}_{4}$, a common elemental form of phosphorus, with $\mathrm{Cl}_{2}$ yields $\mathrm{PCl}_{5} .$ Calculate the mass of $\mathrm{Cl}_{2}$ needed to react completely with $0.567 \mathrm{~g} \mathrm{P}_{4}$.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 122

What mass of $\mathrm{NH}_{3}$ forms from the reaction of $5.33 \mathrm{~g} \mathrm{~N}_{2}$ with excess $\mathrm{H}_{2} ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 123

Aluminum metal reacts with sulfuric acid, $\mathrm{H}_{2} \mathrm{SO}_{4},$ to yield aluminum sulfate and hydrogen gas. Calculate the mass of aluminum metal needed to produce $13.2 \mathrm{~g}$ hydrogen.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 124

Chlorine can be produced in the laboratory by the reaction of hydrochloric acid with excess manganese(IV) oxide. $$\begin{aligned}4 \mathrm{HCl}(\mathrm{aq})+\mathrm{MnO}_{2}(\mathrm{~s}) \rightarrow \\ \mathrm{Cl}_{2}(\mathrm{~g}) &+2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{MnCl}_{2}(\mathrm{aq})\end{aligned}$$ How many moles of $\mathrm{HCl}$ are needed to form $12.5 \mathrm{~mol} \mathrm{Cl}_{2}$ ?

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 125

Lithium metal reacts with $\mathrm{O}_{2}$ to form lithium oxide. What is the theoretical yield of lithium oxide when $0.45 \mathrm{~g}$ lithium reacts with excess $\mathrm{O}_{2}$ ?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 126

In a reaction of $\mathrm{HCl}$ and $\mathrm{NaOH},$ the theoretical yield of $\mathrm{H}_{2} \mathrm{O}$ is $78.2 \mathrm{~g} .$ What is the theoretical yield of $\mathrm{NaCl} ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 127

A mixture of hydrogen and nitrogen gas reacts as shown in the drawing below.
(a) Write the balanced equation.
(b) Which reactant is the limiting reactant?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 128

A mixture of antimony atoms and $\mathrm{Cl}_{2}$ in the gas phase reacts as shown in the drawing below.
(a) Write the balanced equation.
(b) Which reactant is the limiting reactant?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 129

Hydrogen and nitrogen react to form ammonia, $\mathrm{NH}_{3}$. Calculate the mass of $\mathrm{NH}_{3}$ produced from the reaction of $14 \mathrm{~g} \mathrm{~N}_{2}$ and $1.0 \mathrm{~g} \mathrm{H}_{2}$.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 130

Calculate the mass of silver produced if $3.22 \mathrm{~g}$ zinc metal and $4.35 \mathrm{~g} \mathrm{AgNO}_{3}$ react according to the following equation.
$$
\mathrm{Zn}(\mathrm{s})+2 \mathrm{AgNO}_{3}(\mathrm{aq}) \rightarrow 2 \mathrm{Ag}(\mathrm{s})+\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})
$$

Sima Sarker

Numerade Educator

Problem 131

What is the theoretical yield, in grams, of $\mathrm{CO}_{2}$ formed from the reaction of $3.12 \mathrm{~g} \mathrm{CS}_{2}$ and $1.88 \mathrm{~g} \mathrm{O}_{2}$ ? The second product is $\mathrm{SO}_{2}$.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 132

What is the theoretical yield, in grams, of $\mathrm{P}_{4} \mathrm{O}_{10}$ formed from the reaction of $2.2 \mathrm{~g} \mathrm{P}_{4}$ with $4.2 \mathrm{~g} \mathrm{O}_{2} ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 133

In a reaction of $3.3 \mathrm{~g} \mathrm{Al}$ with excess $\mathrm{HCl}, 3.5 \mathrm{~g} \mathrm{AlCl}_{3}$ is isolated (hydrogen gas also forms in this reaction). What is the percent yield of the aluminum compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 134

A reaction of $43.1 \mathrm{~g} \mathrm{CS}_{2}$ with excess $\mathrm{Cl}_{2}$ yields $45.2 \mathrm{~g}$ $\mathrm{CCl}_{4}$ and $41.3 \mathrm{~g} \mathrm{~S}_{2} \mathrm{Cl}_{2} .$ What is the percent yield of each product?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 135

The reaction of $9.66 \mathrm{~g} \mathrm{O}_{2}$ with $9.33 \mathrm{~g}$ NO produces $10.1 \mathrm{~g} \mathrm{NO}_{2}$. What is the percent yield?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 136

The reaction of $7.0 \mathrm{~g} \mathrm{Cl}_{2}$ with $2.3 \mathrm{~g} \mathrm{P}_{4}$ produces $7.1 \mathrm{~g}$ $\mathrm{PCl}_{5}$. What is the percent yield?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 137

The combustion of $33.5 \mathrm{~g} \mathrm{C}_{3} \mathrm{H}_{6}$ with $127 \mathrm{~g} \mathrm{O}_{2}$ yields $16.1 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ What is the percent yield?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 138

Methanol, $\mathrm{CH}_{3} \mathrm{OH},$ is used in racing cars because it is a clean-burning fuel. It can be made by this reaction: $$\mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{CH}_{3} \mathrm{OH}(\ell)$$ What is the percent yield if $5.0 \times 10^{3} \mathrm{~g} \mathrm{H}_{2}$ reacts with excess $\mathrm{CO}$ to form $3.5 \times 10^{3} \mathrm{~g} \mathrm{CH}_{3} \mathrm{OH}$ ?

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 139

The reaction of $23.1 \mathrm{~g} \mathrm{NaOH}$ with $21.2 \mathrm{~g} \mathrm{HNO}_{3}$ yields
a $12.9-\mathrm{g}$ sample of $\mathrm{NaNO}_{3}$
(a) What is the percent yield?
(b) Identify the reactant that is present in excess and calculate the mass of it that remains at the end of the reaction.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 140

When heated, potassium chlorate, $\mathrm{KClO}_{3},$ melts and decomposes to potassium chloride and diatomic oxygen.
(a) What is the theoretical yield of $\mathrm{O}_{2}$ from $3.75 \mathrm{~g}$ $\mathrm{KClO}_{3} ?$
(b) If $1.05 \mathrm{~g}$ of $\mathrm{O}_{2}$ is obtained, what is the percent yield?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 141

The Ostwald process is used to make nitric acid from ammonia. The first step of the process is the oxidation of ammonia as pictured below: In an experiment, $50.0 \mathrm{~g}$ of each reactant is sealed in a container and heated so the reaction goes to completion.
(a) What is the limiting reactant?
(b) How much of the nonlimiting reactant remains after the reaction is completed? Assume that all of the limiting reactant is consumed.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 142

In the second step of the Ostwald process (see previous exercise), the nitrogen monoxide reacts with more $\mathrm{O}_{2}$ to yield nitrogen dioxide. In an experiment, $75.0 \mathrm{~g} \mathrm{NO}$ and $45.0 \mathrm{~g} \mathrm{O}_{2}$ are sealed in a container and heated so the reaction goes to completion.
(a) What is the limiting reactant?
(b) How much of the nonlimiting reactant remains after the reaction is complete? Assume that all of the limiting reactant is consumed.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 143

A $2.24-g$ sample of an unknown metal reacts with $\mathrm{HCl}$ to produce $0.0808 \mathrm{~g} \mathrm{H}_{2}$ gas. The reaction is $\mathrm{M}+$ $2 \mathrm{HCl} \rightarrow \mathrm{MCl}_{2}+\mathrm{H}_{2}$. Assuming that the percent yield
of product is $100 \%$, identify the metal.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 144

A $3.11-\mathrm{g}$ sample of one of the halogens, $\mathrm{X}_{2}$, is shown to react with $\mathrm{NaOH}$ to produce $2.00 \mathrm{~g} \mathrm{NaX}$. The equation is $2 \mathrm{NaOH}+\mathrm{X}_{2} \rightarrow \mathrm{NaX}+\mathrm{NaXO}+\mathrm{H}_{2} \mathrm{O} .$ Assuming that the percent yield of product is $100 \%$, identify the halogen.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 145

Predict the formula of an ionic compound formed from calcium and nitrogen. Calculate the mass percentage composition of the elements in this compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 146

Write the formula of iron(III) sulfate and calculate the mass percentage of each element in the compound.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 147

A Copper can be commercially obtained from an ore that contains 10.0 mass percent chalcopyrite, $\mathrm{CuFeS}_{2}$, as the only source of copper. How many tons of the ore are needed to produce 20.0 tons of $99.0 \%$ pure copper?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 148

$\mathrm{In}_{2} \mathrm{~S}_{3}$ can be converted into metallic indium by a twostep process. First, it is converted into $\mathrm{In}_{2} \mathrm{O}_{3}$ by reaction with oxygen. The other product of the reaction is $\mathrm{SO}_{2}$. Indium metal is obtained by reaction of $\mathrm{In}_{2} \mathrm{O}_{3}$ with carbon. Assume that the other product of the second reaction is carbon dioxide.
(a) Write the two equations for this process.
(b) Calculate the mass, in kilograms, of indium produced from $35.7 \mathrm{~kg} \operatorname{In}_{2} \mathrm{~S}_{3}$, assuming excesses of the other reactants.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 149

Some ionic compounds exist in crystalline form with a certain number of water molecules associated with the ions. Such compounds are called bydrates. For example, calcium sulfate can exist with either one-half water molecule per formula unit, written as $\mathrm{CaSO}_{4} \cdot 1 / 2 \mathrm{H}_{2} \mathrm{O}$ or two water molecules per formula unit, written as $\mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O} .$ What is the percentage water (by mass) for each compound?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 150

A hydrate (see previous exercise) can be heated to drive off the water molecules from the crystal. A sample of hydrated magnesium sulfate with an initial mass of $3.650 \mathrm{~g}$ was placed in a crucible and heated with a Bunsen burner. After thorough heating, the mass of the solid remaining was $1.782 \mathrm{~g}$. How many water molecules are associated with each formula unit of hydrated magnesium sulfate?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 151

A backup system on the space shuttle that removes carbon dioxide is canisters of $\mathrm{LiOH}$. This compound reacts with $\mathrm{CO}_{2}$ to produce $\mathrm{Li}_{2} \mathrm{CO}_{3}$ and water. How many grams of $\mathrm{CO}_{2}$ can be removed from the atmosphere by a canister that contains $83 \mathrm{~g} \mathrm{LiOH}$ ?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 152

Copper sulfate is generally isolated as its hydrate, $\mathrm{CuSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O} .$ If a sample contains $25.5 \% \mathrm{Cu}, 12.8 \% \mathrm{~S},$ $57.7 \% \mathrm{O},$ and $4.04 \% \mathrm{H},$ what is the value of $x ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 153

The compound dinitrogen monoxide, $\mathrm{N}_{2} \mathrm{O}$, is a nontoxic gas that is used as the propellant in cans of whipped cream. How many nitrogen atoms are in a 34.7-g sample of $\mathrm{N}_{2} \mathrm{O}$ ?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 154

Morphine is a narcotic substance that has been used medically as a painkiller. Its use has been highly restricted because of its addictive nature. Morphine is $71.56 \% \mathrm{C}, 6.71 \% \mathrm{H}, 4.91 \% \mathrm{~N},$ and $16.82 \% \mathrm{O},$ and its molar mass is $285 \mathrm{~g} / \mathrm{mol}$. What is its molecular formula?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 155

Fill in the blanks in the following table.

James Irizarry

Numerade Educator

Problem 156

Heating $\mathrm{NaWCl}_{6}$ at $300^{\circ} \mathrm{C}$ converts it into $\mathrm{Na}_{2} \mathrm{WCl}_{6}$ and $\mathrm{WCl}_{6}$. If the reaction of $5.64 \mathrm{~g} \mathrm{NaWCl}_{6}$ produces $1.52 \mathrm{~g} \mathrm{WCl}_{6}$, what is the percentage yield?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 157

The compound $\mathrm{K}\left[\mathrm{Pt} \mathrm{Cl}_{3}\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)\right]$ was first prepared by a
Danish pharmacist around 1830 . Scientists have only recently determined its structure. This complex is now known to be the first example of an important class of compounds known as organometallics. It can be prepared by the reaction of $\mathrm{K}_{2}\left[\mathrm{Pt} \mathrm{Cl}_{4}\right]$ with ethylene, $\mathrm{C}_{2} \mathrm{H}_{4}$. The other product is potassium chloride.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 158

A Many important chemical processes require two (or more) steps. One example is a process used to determine the amount copper in a sample. Many copper compounds, dissolved in water, will react with zinc metal to yield copper metal and a water-soluble zinc compound. $$ \mathrm{CuSO}_{4}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s}) \rightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{ZnSO}_{4}(\mathrm{aq}) $$ The metallic copper is collected and weighed, whereas the $\mathrm{ZnSO}_{4}$ stays in the water in which the reaction takes place. To ensure that all of the copper is converted to the metallic form, an excess of zinc is added to the reaction. The excess zinc must be removed before the weight of the copper is determined because it is also a solid. An excess of $\mathrm{H}_{2} \mathrm{SO}_{4}$ is added to remove the zinc. This acid will react with the zinc metal but not the copper metal. $$ \mathrm{Zn}(\mathrm{s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})$$ With the solid zinc thus removed, the copper metal is weighed and the mass used to find the percentage copper. What is the percent of copper in a hydrated sample of the formula $\mathrm{CuSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}(x=$ unknown number of water molecules), if a $1.20-\mathrm{g}$ sample reacts with excess zinc followed by addition of excess $\mathrm{H}_{2} \mathrm{SO}_{4}$ to yield $0.306 \mathrm{~g}$ copper metal? What is the value of $x ?$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 159

Molecular nitrogen can be converted to NO in two steps. The equations follow. These two reactions are the first steps in the industrially important conversion of nitrogen into nitric acid. Calculate the mass of $\mathrm{NO}$ formed from $100 \mathrm{~g} \mathrm{~N}_{2}$ and excess $\mathrm{H}_{2}$ and $\mathrm{O}_{2}$.
$$
\begin{array}{l}
\mathrm{N}_{2}+3 \mathrm{H}_{2} \rightarrow 2 \mathrm{NH}_{3} \\
4 \mathrm{NH}_{3}+5 \mathrm{O}_{2} \rightarrow 4 \mathrm{NO}+6 \mathrm{H}_{2} \mathrm{O}
\end{array}
$$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 160

The reaction of sulfur dichloride and sodium fluoride yields sulfur tetrafluoride, disulfur dichloride, and sodium chloride. Write the balanced equation. What mass of sulfur tetrafluoride is formed by the reaction of $12.44 \mathrm{~g}$ sulfur dichloride and $10.11 \mathrm{~g}$ sodium fluoride?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 161

The reaction of equal molar amounts of benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$ and chlorine, $\mathrm{Cl}_{2},$ carried out under special conditions completely consumes the reactants and yields a gas and a clear liquid. Analysis of the liquid shows that it contains $64.03 \%$ carbon, $4.48 \%$ hydrogen, and $31.49 \%$ chlorine, and has a molar mass of $112.5 \mathrm{~g} / \mathrm{mol}$. Write the balanced equation for this reaction.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 162

Although copper does not usually react with acids, it does react with concentrated nitric acid. The reaction is complicated, but one outcome is $$\begin{aligned}\mathrm{Cu}(\mathrm{s})+\mathrm{HNO}_{3}(\mathrm{conc}) \rightarrow \\& \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell)\end{aligned}$$
(a) Name all of the reactants and products.
(b) Balance the reaction.
(c) Assign oxidation numbers to the atoms. Is this a redox reaction?
(d) Pre-1983 pennies were made of pure copper. If such a penny had a mass of $3.10 \mathrm{~g}$, how many moles of Cu are in one penny? How many atoms of copper are in one penny?
(e) What mass of $\mathrm{HNO}_{3}$ would be needed to completely react with a pre-1983 penny?

Adriano Chikande

Adriano Chikande

Numerade Educator