Quiz – Stoichiometry

Have you mastered calculating reactants and products? Put your stoichiometry skills to the test with a quiz.

Your turn – stoichiometry calculations

1. $\mathrm{CO}$ reacts with ${\mathrm{O}}_2$ to form ${\mathrm{CO}}_2$ gas as shown by the equation:
   $$2\mathrm{CO}+{\mathrm{O}}_2\to 2{\mathrm{CO}}_2$$
1. Calculate the amount in moles of $\mathrm{O}{\phantom{A}}_2$ required to react with $0.58\text{ mol}$ of $\mathrm{CO}$.

Answer

$0.29\text{ mol}$

2. Calculate the amount in moles of $\mathrm{CO}{\phantom{A}}_2$ produced when $0.35\text{ mol}$ or $\mathrm{CO}$ reacts with $\mathrm{O}{\phantom{A}}_2$.

Answer

$0.35\text{ mol}$

3. Calculate the amount in moles of $\mathrm{O}{\phantom{A}}_2$ that must react with $\mathrm{CO}$ to produce $0.49\text{ mol}$ or $\mathrm{CO}{\phantom{A}}_2$.

Answer

$0.24\text{ mol}$

2. The reaction between hydrazine and oxygen gas produces nitric oxide and water vapour according to the following balanced chemical equation:
   $${\mathrm{N}}_2{\mathrm{H}}_4\left(\text{l}\right)+3{\mathrm{O}}_2\left(\text{g}\right)\to 2{\mathrm{NO}}_2\left(\text{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\text{g}\right)$$
1. Calculate the amount in moles of ${\mathrm{O}}_2$ required to react with $0.6\text{ mol}$ of ${\mathrm{N}}_2{\mathrm{H}}_4$.

Answer

$2\text{ mol}$

2. Calculate the amount in moles of ${\mathrm{N}}_2{\mathrm{H}}_2$ that must react with ${\mathrm{O}}_2$ to form $0.4\text{ mol}$ of ${\mathrm{NO}}_2$.

Answer

$0.2\text{ mol}$

3. Calculate the mass of ${\mathrm{O}}_2$ required to form $10.50\text{ g}$ of ${\mathrm{CO}}_2$ from the reaction between methane and oxygen:
   $${\mathrm{CH}}_4+2{\mathrm{O}}_2\to {\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$$
   The molar masses of ${\mathrm{CO}}_2$ and ${\mathrm{O}}_2$ are $44.01{\text{ g mol}}^{-1}$ and $32.00{\text{ g mol}}^{-1}$.

4. Consider the equation for the following chemical reaction:
   $$3{\mathrm{H}}_2\left(\text{g}\right)+{\mathrm{N}}_2\left(\text{g}\right)\to 2{\mathrm{NH}}_3\left(\text{g}\right)$$
   Calculate the mass of ${\mathrm{N}}_2$ required to produce $48.5\text{ g}$ of ${\mathrm{NH}}_3$. The molar masses of ${\mathrm{NH}}_3$ and ${\mathrm{N}}_2$ are $17.03{\text{ g mol}}^{-1}$ and $28.02{\text{ g mol}}^{-1}$.

5. Sulfur dioxide gas is produced by the reaction between sulfur and oxygen:
   $$\mathrm{S}+{\mathrm{O}}_2\to {\mathrm{SO}}_2$$
   $12.8\text{ g}$ of $\mathrm{S}$ reacts with $18.5\text{ g}$ of ${\mathrm{O}}_2$. The molar masses of $\mathrm{S}$ and ${\mathrm{O}}_2$ are $32.07{\text{ g mol}}^{-1}$ and $32.00{\text{ g mol}}^{-1}$, respectively. The molar mass of $\mathrm{SO}{\phantom{A}}_2$ is $64.07{\text{ g mol}}^{-1}$.
1. Identify the limiting reagent.

Answer

$\mathrm{S}$

2. Calculate the maximum mass of ${\mathrm{SO}}_2$ that can be formed under the given conditions.

Answer

$25.63\text{ g}$

6. $\mathrm{HCl}$ is formed according to the following reaction.
   $${\mathrm{H}}_2+{\mathrm{Cl}}_2\to 2\mathrm{HCl}$$
   Calculate the maximum mass of $\mathrm{HCl}$ that can be produced when $0.85\text{ g}$ of ${\mathrm{H}}_2$ reacts with $42.58\text{ g}$ of ${\mathrm{Cl}}_2$. The atomic molar masses of $\mathrm{H}$ and $\mathrm{Cl}$ are $1.01{\text{ g mol}}^{-1}$ and $35.45{\text{g mol}}^{-1}$.

7. Calcium nitrite (${\mathrm{Ca}}_3{\mathrm{N}}_2$) is produced using $\mathrm{Ca}$ and ${\mathrm{N}}_2$ as follows:
   $$3\mathrm{Ca}+{\mathrm{N}}_2\to {\mathrm{Ca}}_3{\mathrm{N}}_2$$
   Calculate the theoretical yield of ${\mathrm{Ca}}_3{\mathrm{N}}_2$ when $120.56\text{ g}$ of $\mathrm{Ca}$ is reacted with $42.87\text{ g}$ of ${\mathrm{N}}_2$. The atomic molar mass of $\mathrm{Ca}$ is $40.08{\text{g mol}}^{-1}$, and the atomic molar mass of $\mathrm{N}$ is $14.01{\text{g mol}}^{-1}$. The molar mass of ${\mathrm{Ca}}_3{\mathrm{N}}_2$ is $148.26{\text{g mol}}^{-1}$.

8. Salicylic acid (${\mathrm{C}}_7{\mathrm{H}}_6{\mathrm{O}}_3$) reacts with acetic anhydride (${\mathrm{C}}_4{\mathrm{H}}_6{\mathrm{O}}_3$) to form acetylsalicylic acid (${\mathrm{C}}_9{\mathrm{H}}_8{\mathrm{O}}_4$), which we call aspirin.
   $$2{\mathrm{C}}_7{\mathrm{H}}_6{\mathrm{O}}_3+{\mathrm{C}}_4{\mathrm{H}}_6{\mathrm{O}}_3\to 2{\mathrm{C}}_9{\mathrm{H}}_8{\mathrm{O}}_4+{\mathrm{H}}_2\mathrm{O}$$
   The percentage yield of aspirin from the reaction is $88.48\mathrm{\%}$. Determine the mass of aspirin that was actually formed by the reaction of $250.82\text{ g}$ of salicylic acid. The molar masses of salicylic acid and acetylsalicylate acid are $138.21{\text{ g mol}}^{-1}$ and $180.16\text{ g}$, respectively.