Assessment and Evalution
Lesson: Chapter 9 Stoichiometry
Resource:HRW Modern Chemistry

Chapter 9 Stoichiometry
Circle the letter of the best answer

1. Which statement is true?

a Mole ratios limit the number of significant figures in a calculation.
b You must know the masses of all the reactants in a chemical equation in order to determine the masses of all the products
c The mole ratio is needed only to solve problems in which the given is a mass in grams and the unknown is an amount in moles.
d A mole ratio can only be determined from a correctly balanced chemical equation

2. Antoine Laurent Lavoisier’s contribution to chemistry was
a the law of conservation of mass.
b the law of conservation of energy.
c the periodic table of elements.
d the phlogiston theory of combustion

3. For the general chemical equation 2A + 3B �� 4C + D, how many moles of A are required to produce 18.4 mol of C ?

a 9.2 mol
b 13.8 mo
c 36.8 mol
d 73.6 mol

4. For the chemical reaction represented by the equation C 8 H 8 + 5O 2 �� 3CO 2 + 4H 2 O, how many moles of O 2 are required to react with 16.4 moles of C 8 H 8 ?
a. 3.28 mol
b. 21.4 mol
c. 65.6 mol
d. 82 mol

5. The reaction N 2 + 3H 2 �� 2NH 3 is run using 184.6 g of N 2 . How many moles of NH 3 are formed ?
a. 6.59 mol
b. 13.18 mo
c. 5 mol
d. 369.2 mol

6. If 4.2 moles of NaNO 3 are used in the reaction 2NaNO 3 �� 2NaNO 2 + O 2 , how many grams of NaNO 2 are produced?

a. 8.4 g
b. 138 g
c. 289.8 g
d. 579.6 g

7. Given the balanced equation 2C 4 H 10 + 13O 2 �� 8CO 2 + 10H 2 O, how many moles of CO2 are
produced when 14.9 g of O 2 are used?

a 0.29 mol
b 3.49 mol
c 12.61 mol
d 119.2 mol

8. Which statement is true?
a The inverted molar mass is the conversion factor used to convert from moles to grams.
b The mass of a substance is expressed in moles.
c Moles and grams are units, while mass is a quantity.
d For any given chemical equation, all of the reactant is converted to product.

9.Given the general chemical equation A + 2B �� 2C + D, what is the limiting reactant if
2.0 mol of Aare exposed to 6.2 mol of B?
a. A
b. B
c. C
d. D

10. Given the general chemical equation 2A + 3B �� 2C + 6D, what is the excess reactant if 4.3 mol of A are exposed to 5.4 mol of B?
a. A
b. B
c. C
d. D

11. Given the equation Cu 2 S + O 2 �� 2Cu + SO 2 , what is the theoretical yield of SO 2 if 8.20 g of O 2 are used?
a. 0.26 g
b. 2.26 g
c. 16.40 g
d. none of the above

12. If 4.2 mol of NH 3 and 6.8 mol of O 2 are used in the reaction 4NH 3 + 5O 2 �� 4NO + 6H 2 O, then which o f these statements is not true?
a. O 2 is the excess reactant.
b. The theoretical yield of H 2 O is 113.53 grams.
c. The theoretical yield of H 2 O is 113.53 mol.
d. The theoretical yield of NO is 1 mol.

 

 

 

 

Return to top menu