Stoichiometry Review


Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.


d 1. Which branch of chemistry deals with the mass relationships of elements in compounds and the mass relationships among reactants and products in chemical reactions?

a.

qualitative analysis

c.

chemical kinetics

b.

entropy

d.

stoichiometry



b 2. What is the study of the mass relationships of elements in compounds?

a.

reaction stoichiometry

c.

percent yield

b.

composition stoichiometry

d.

Avogadro's principle



___c_ 3. Which of the following would be investigated in reaction stoichiometry?

a.

the masses of hydrogen and oxygen in water

b.

the amount of energy released in chemical reactions

c.

the mass of potassium required to produce a known mass of potassium chloride

d.

the types of bonds that break and form when acids react with metals



a 4. A balanced chemical equation allows one to determine the

a.

mole ratio of any two substances in the reaction.

b.

energy released in the reaction.

c.

electron configuration of all elements in the reaction.

d.

mechanism involved in the reaction.



b 5. The coefficients in a chemical equation represent the

a.

masses, in grams, of all reactants and products.

b.

relative numbers of moles of reactants and products.

c.

number of atoms in each compound in a reaction.

d.

number of valence electrons involved in the reaction.



d 6. Each of the four types of reaction stoichiometry problems requires using a

a.

table of bond energies.

c.

Lewis structure.

b.

chart of electron configurations.

d.

mole ratio.



D 7. In the reaction 2Al2O3 → 4Al + 3O2, what is the mole ratio of aluminum to oxygen?

a.

10:6

c.

2:3

b.

3:4

d.

4:3



A__ 8. In the reaction 2H2 + O2 → 2H2O, what is the mole ratio of oxygen to water?

a.

1:2

c.

8:1

b.

2:1

d.

1:4



B 9. In the reaction Zn + H2SO4 → ZnSO4 + H2, what is the mole ratio of zinc to sulfuric acid?

a.

1:6

c.

1:2

b.

1:1

d.

3:1



C__ 10. In the reaction N2 + 3H2 → 2NH3, what is the mole ratio of hydrogen to ammonia?

a.

1:1

c.

3:2

b.

2:1

d.

6:8



A__ 11. For the reaction CH4 + 2O2 → 2H2O + CO2, calculate the percent yield of carbon dioxide if 1000. g of methane react with excess oxygen to produce 2300. g of carbon dioxide.

a.

83.88%

c.

92.76%

b.

89.14%

d.

96.78%



___C_ 12. For the reaction 2Na + 2H2O → 2NaOH + H2, calculate the percent yield if 80. g of water react with excess sodium to produce 4.14 g of hydrogen.

a.

87%

c.

92%

b.

89%

d.

98%



D 13. Which reactant controls the amount of product formed in a chemical reaction?

a.

excess reactant

c.

composition reactant

b.

mole ratio

d.

limiting reactant



B 14. A chemical reaction involving substances A and B stops when B is completely used. B is the

a.

excess reactant.

c.

primary reactant.

b.

limiting reactant.

d.

primary product.



___B_ 15. What is the ratio of the actual yield to the theoretical yield, multiplied by 100%?

a.

mole ratio

c.

Avogadro yield

b.

percent yield

d.

excess yield



A 16. What is the measured amount of a product obtained from a chemical reaction?

a.

mole ratio

c.

theoretical yield

b.

percent yield

d.

actual yield



___D_ 17. What is the maximum possible amount of product obtained in a chemical reaction?

a.

theoretical yield

c.

mole ratio

b.

percent yield

d.

actual yield



C 18. A chemist interested in the efficiency of a chemical reaction would calculate the

a.

mole ratio.

c.

percent yield.

b.

energy released.

d.

rate of reaction.



Problem


19. What mass in grams of sodium hydroxide is produced if 20.0 g of sodium metal reacts with excess water according to the chemical equation 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)?

34.8g 



20. What mass in grams of hydrogen gas is produced if 20.0 mol of Zn are added to excess hydrochloric acid according to the equation Zn(s) +2HCl(aq) → ZnCl2(aq) + H2(g)

40.4g