Chemical Quantities and Reactions

Identify each of the following as an oxidation or a reduction: ($7.6$)

a. ${\mathrm{Mg}}^{2+}\left(\mathrm{aq}\right) + 2{\mathrm{e}}^{-} \to \mathrm{Mg}\left(\mathrm{s}\right)$

b. $2{\mathrm{I}}^{-}\left(\mathrm{aq}\right) \to {\mathrm{I}}_2\left(\mathrm{s}\right) +2{\mathrm{e}}^{-}$

c. $\mathrm{Li}\left(\mathrm{s}\right)\to {\mathrm{Li}}^{+} \left(\mathrm{aq}\right) + {\mathrm{e}}^{-}$

d. ${\mathrm{Co}}^{2+}\left(\mathrm{aq}\right) + 2{\mathrm{e}}^{-} \to \mathrm{Co}\left(\mathrm{s}\right)$

When ammonia (${\mathrm{NH}}_3$) gas reacts with fluorine gas, the gaseous products are dinitrogen tetrafluoride (${\mathrm{N}}_2{\mathrm{F}}_4$) and hydrogen fluoride ($\mathrm{HF}$). ($7.4, 7.7, 7.8$)

a. Write the balanced chemical equation.

b. How many moles of each reactant are needed to produce $4.00$ mole of $\mathrm{HF}$?

c. How many grams of ${\mathrm{F}}_2$ are needed to react with $25.5$ g of ${\mathrm{NH}}_3$?

d. How many grams of ${\mathrm{N}}_2{\mathrm{F}}_4$ can be produced when $3.40$ g of ${\mathrm{NH}}_3$ reacts?

A toothpaste contains $0.240 \%$ by mass sodium fluoride used to prevent dental caries and $5.0 \%$ by mass ${\mathrm{KNO}}_3$, which decreases pain sensitivity. One tube contains $119 g$ of toothpaste
$\mathrm{NaF}$ and ${\mathrm{KNO}}_3$ are components found in toothpastes.

1. How many moles of $\mathrm{NaF}$ are in the tube of toothpaste?
2. How many fluoride ions, ${\mathrm{F}}^{-}$, are in the tube of toothpaste?
3. How many grams of sodium ion, ${\mathrm{Na}}^{+}$, are in $1.50 g$ of toothpaste?
4. How many ${\mathrm{KNO}}_3$ formula units are in the tube of toothpaste? 

Consider the following unbalanced equation: 

$\mathrm{Al}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)$

1.  Write the balanced chemical equation. 
2.  Identify the type of reaction. 
3.  How many moles of ${\mathrm{O}}_2$ are needed to react with $4.50$ moles of $\mathrm{Al}$ ?
4.  How many grams of ${\mathrm{Al}}_2{\mathrm{O}}_3$ are produced when $50.2 g$ of $\mathrm{Al}$ reacts?
5. When $\mathrm{Al}$ is reacted with $8.00 g$ of ${\mathrm{O}}_2$, how many grams of ${\mathrm{Al}}_2{\mathrm{O}}_3$ can form? 

During heavy exercise and workouts, lactic acid, ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_3$, accumulates in the muscles where it can cause pain and soreness.

a. How many molecules are in $0.500$ mole of lactic acid?
b. How many atoms of $\mathrm{C}$ are in $1.50$ moles of lactic acid?
c. How many moles of lactic acid contain $4.5\times {10}^{24}$atoms of $\mathrm{O}$ ?
d. What is the molar mass of lactic acid?

When nitrogen dioxide (${\mathrm{NO}}_2$) gas from car exhaust combines with water vapor in the air, it forms aqueous nitric acid (${\mathrm{HNO}}_3$), which causes acid rain, and nitrogen oxide gas. ($7.4, 7.7, 7.8$)

a. Write the balanced chemical equation. 

b. How many moles of each product are produced from $0.250$ mole of ${\mathrm{H}}_2\mathrm{O}$?

c. How many grams of ${\mathrm{HNO}}_3$ are produced when $60$ g of ${\mathrm{NO}}_2$ completely reacts?

d. How many grams of ${\mathrm{NO}}_2$ are needed to form $75.0$ g of ${\mathrm{HNO}}_3$?

Pentane gas, ${\mathrm{C}}_5{\mathrm{H}}_{12}$, undergoes combustion with oxygen gas to produce carbon dioxide and water gases. ($7.4, 7.8$)

a. Write the balanced chemical equation. 

b. How many grams of ${\mathrm{C}}_5{\mathrm{H}}_{12}$ are needed to produce $72$ g of water?

c. How many grams of ${\mathrm{CO}}_2$ are produced from $32.0$ g of ${\mathrm{O}}_2$?

The equation for the formation of silicon tetrachloride from silicon and chlorine is ($7.9$)

data-custom-editor="chemistry" $\mathrm{Si}\left(\mathrm{s}\right) + 2{\mathrm{Cl}}_2\left(\mathrm{g}\right) \to {\mathrm{SiCl}}_4\left(\mathrm{g}\right) + 157 \mathrm{kcal}$

a. Is the formation of data-custom-editor="chemistry" ${\mathrm{SiCl}}_4$, an endothermic or exothermic reaction?

b. Is the energy of the product higher or lower than the energy of the reactants?

The equation for the formation of nitrogen oxide is ($7.9$) 

data-custom-editor="chemistry" ${\mathrm{N}}_2\left(\mathrm{g}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) +90.2 \mathrm{kJ} \to 2\mathrm{NO}\left(\mathrm{g}\right)$

a. Is the formation of data-custom-editor="chemistry" $\mathrm{NO}$ an endothermic or exothermic reaction?

b. Is the energy of the product higher or lower than the energy of the reactants?

At a winery, glucose (${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$) in grapes undergoes fermentation to produce ethanol (${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$) and carbon dioxide. ($7.8$)

$$\begin{gathered} {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{aq}\right)\to 2{\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}\left(\mathrm{aq}\right) + 2{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{Glucose} \mathrm{Ethanol} \end{gathered}$$

Glucose in grapes ferments to produce ethanol.

a. How many grams of glucose are required to form $124$ g of ethanol? 

b. How many grams of ethanol would be formed from the reaction of $0.240$ kg of glucose?

Gasohol is a fuel containing liquid ethanol (${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$) that burns in oxygen gas to give carbon dioxide and water gases. ($7.4, 7.7, 7.8$)

a. Write the balanced chemical equation.

b. How many moles of ${\mathrm{O}}_2$ are needed to completely react with style="max-width: none; vertical-align: -4px;" $4.0$ mole of ${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$?

c. If a car produces style="max-width: none; vertical-align: -4px;" $88$ g of ${\mathrm{CO}}_2$, how many grams of ${\mathrm{O}}_2$ are used up in the reaction?

d. If you burn $125$ g of ${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$, how many grams of ${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$ can be produced?

Consider the following unbalanced equation: ($7.4, 7.5, 7.7, 7.8$)

$\mathrm{Al}\left(\mathrm{s}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) \to {\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)$

a. Write the balanced chemical equation. 

b. Identify the type of reaction.

c. How many moles of $O_2$ are needed to react with $4.50$ mole of $\mathrm{Al}$?

d. How many grams of ${\mathrm{Al}}_2{\mathrm{O}}_3$ are produced when $50.2$ g of $\mathrm{Al}$ reacts?

e. When $\mathrm{Al}$ is reacted with $8.00$ g  of ${\mathrm{O}}_2$, how many grams of $A{l}_2{O}_3$ can form?

Liquid methanol ${\mathrm{CH}}_4\mathrm{O}$, which is used as a cooking fuel, burns with oxygen gas to produce the gases carbon dioxide and water. The reaction produces $363 \mathrm{kJ}$ of heat per mole of methanol.
a. Write a balanced equation for the reaction, including the heat of reaction.
b. Is the reaction endothermic or exothermic?
c. How many moles of ${\mathrm{O}}_2$ must react with $0.450$  mole of ${\mathrm{CH}}_4\mathrm{O}$
d. How many grams of ${\mathrm{CO}}_2$ are produced when $78.0 \mathrm{g}$ of ${\mathrm{CH}}_4\mathrm{O}$ reacts?

Acetylene gas, ${\mathrm{C}}_2{\mathrm{H}}_2$, used in welders' torches, releases $1300 \mathrm{kJ}$ of heat when one mole of ${\mathrm{C}}_2{\mathrm{H}}_2$ undergoes combustion.
a. Write a balanced equation for the reaction, including the heat of reaction.
b. Is the reaction endothermic or exothermic?

c. How many moles of ${\mathrm{H}}_2\mathrm{O}$ are produced when  $2.00$ moles of ${\mathrm{O}}_2$ reacts?
d. How many grams of ${\mathrm{O}}_2$ are needed to react with $9.80 \mathrm{g}$ of ${\mathrm{C}}_2{\mathrm{H}}_2$

Ammonium sulfate, ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4$, is used in fertilizers to provide nitrogen for the soil.
a. How many formula units are in $0.200$ mole of ammonium sulfate?
b. How many $\mathrm{H}$ atoms are in $0.100$ mole of ammonium sulfate?
c. How many moles of ammonium sulfate contain $7.4\times {10}^{25}$ atoms of $\mathrm{N}$ ?
d. What is the molar mass of ammonium sulfate?