Name:    Practice Test #6 - Balancing & Stoichiometry

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

1.

The combustion of propane produces carbon dioxide and steam.
C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(g)
All of the following statements concerning this reaction are correct EXCEPT
 a. three molecule of carbon dioxide are formed per one molecule of propane consumed. b. five molecules of oxygen are consumed per one molecule of propane consumed. c. four moles of steam are formed per five moles of oxygen consumed. d. the combined mass of reactants consumed equals the mass of products formed. e. three grams of carbon dioxide are formed per five grams of oxygen consumed.

2.

Ammonia is prepared by reacting nitrogen and hydrogen gases at high temperature according to the unbalanced chemical equation below.
__ N2(g) + __ H2(g) __ NH3(g)
What are the respective coefficients when the equation is balanced with the smallest whole numbers?
 a. 1, 1, 1 b. 1, 3, 1 c. 1, 3, 2 d. 2, 1, 2 e. 2, 3, 2

3.

When methanol undergoes complete combustion, the products are carbon dioxide and water.
__ CH3OH(l) + __ O2(g) __ CO2(g) + __ H2O(g)
What are the respective coefficients when the equation is balanced with the smallest whole numbers?
 a. 1, 1, 1, 1 b. 1, 2, 1, 2 c. 2, 2, 2, 4 d. 2, 3, 2, 4 e. 2, 4, 6, 4

4.

The reaction of calcium with elemental chlorine yields calcium chloride. Write a balanced chemical equation for this reaction.
 a. Ca(s) + Cl2(g) → CaCl(s) + Cl(g) b. Ca(s) + Cl2(g) → CaCl2(s) c. Ca(s) + 2 Cl2(g) → CaCl4(s) d. 2 Ca(s) + Cl2(g) → 2 CaCl(s) e. 4 Ca(s) + Cl2(g) → 2 Ca2Cl(s)

5.

Metals react with oxygen to give oxides with the general formula MxOy. Write a balanced chemical equation for the reaction of iron with oxygen to yield iron(III) oxide.
 a. Fe(s) + O2(g) → FeO2(s) b. 2 Fe(s) + 3 O2(g) → Fe2O3(s) c. 3 Fe(s) + O2(g) → Fe3O2(s) d. 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) e. 6 Fe(s) + O2(g) → 2 Fe3O(s)

6.

The products of the complete combustion of a hydrocarbon are carbon dioxide and water. Write a balanced chemical equation for the combustion of pentane, C5H12.
 a. C5H12(g) + 8 O2(g) → 5 CO2(g) + 6 H2O(g) b. C5H12(g) → 5 C(s) + 6 H2(g) c. C5H12(g) + 9 O2(g) → 4 CO2(g) + 5 H2O(g) d. C5H12(g) + 11 O2(g) → C5O10(g) + 6 H2O(g) e. C5H12(g) + 11 O2(g) → 5 CO2(g) + 12 H2O(g)

7.

The balanced equation for the complete combustion of benzene, C6H6, is
 a. C6H6(l) → 6 C(s) + 3 H2(g) b. C6H6(l) + 12 H2O(l) → 6 CO2(g) + 15 H2(g) c. C6H6(l) + O2(g) → CO2(g) + H2O(g) d. 2 C6H6(l) + 9 O2(g) → 12 CO (g) + 6 H2O(g) e. 2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g)

8.

Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas.
Fe(s) + 2 HCl(aq) FeCl2(aq) + H2(g)
How many moles of HCl will react with 4.6 moles of Fe?
 a. 2.3 mol b. 2.8 mol c. 4.6 mol d. 6.9 mol e. 9.2 mol

9.

The complete combustion of 0.40 moles of butane gas, C4H10, will
 a. consume 0.40 mol O2 and produce 0.20 mol CO2. b. consume 0.80 mol O2 and produce 0.40 mol CO2. c. consume 1.3 mol O2 and produce 0.80 mol CO2. d. consume 2.6 mol O2 and produce 1.6 mol CO2. e. consume 5.2 mol O2 and produce 3.2 mol CO2.

10.

The reaction of water and coal at a high temperature produces a mixture of hydrogen and carbon monoxide gases. This mixture is known as synthesis gas (or syngas). What mass of hydrogen gas can be formed from the reaction of 51.3 g of carbon with excess water?
C(s) + H2O(g) H2(g) + CO(g)
 a. 4.31 g b. 8.61 g c. 17.2 g d. 1.20 ´ 102 g e. 306 g

11.

What mass of carbon dioxide is produced by the complete combustion of 5.50 grams of hexane, C6H14?
 a. 0.468 g b. 2.81 g c. 3.06 g d. 16.9 g e. 33.7 g

12.

What mass of oxygen is consumed by the complete combustion of 23.0 grams of ethylene?
C2H4(g) + 3 O2(g) 2 CO2(g) + 2 H2O(g)
 a. 8.75 g b. 26.2 g c. 60.5 g d. 69.0 g e. 78.7 g

13.

What is a correct method for determining how many moles of calcium oxide are produced in the reaction of 10.0 g calcium with excess oxygen?
2 Ca(s) + O2(g) 2 CaO(s)
 a. 10.0 g Ca = b. 10.0 g Ca = c. 10.0 g Ca = d. 10.0 g Ca = e. 10.0 g Ca =

14.

How many moles of potassium bromide can be produced from the reaction of 2.92 moles of potassium with 1.78 moles of bromine gas?
2 K(s) + Br2(g) 2 KBr(s)
 a. 1.46 mol b. 1.78 mol c. 2.92 mol d. 3.56 mol e. 5.84 mol

15.

How many moles of Fe2O3(s) can be produced from the reaction of 0.45 mol Fe(s) with 0.30 mol O2(g)?
 a. 0.15 mol b. 0.20 mol c. 0.23 mol d. 0.45 mol e. 0.75 mol

16.

Nitric oxide is made from the oxidation of ammonia. How many moles of nitric oxide can be made from the reaction of 3.80 mol NH3 with 5.15 mol O2?

4 NH3(g) + 5 O2(g) 4 NO(g) + 6 H2O(g)

 a. 3.80 mol b. 4.12 mol c. 5.15 mol d. 6.44 mol e. 8.95 mol

17.

Sulfur trioxide is made from the reaction of sulfur dioxide and oxygen. How many grams of SO3 can be made from the reaction of 3.00 g SO2 with 2.02 g O2?
2 SO2(g) + O2(g) 2 SO3(g)
 a. 2.53 g b. 3.75 g c. 5.02 g d. 5.05 g e. 10.1 g

18.

Magnesium reacts with iodine gas at high temperatures to form magnesium iodide. What mass of MgI2 can be produced from the reaction of 4.44 g Mg and 13.4 g I2?
 a. 2.76 g b. 14.7 g c. 16.0 g d. 17.8 g e. 50.8 g

19.

The reaction of 10.0 g H2(g) with 10.0 g O2(g) yields 8.43 g H2O(g). What is the percent yield of this reaction?
 a. 9.43% b. 27.3% c. 42.2% d. 66.8% e. 74.9%

20.

Aspirin is produced by the reaction of salicylic acid (M = 138.1 g/mol) and acetic anhydride (M = 102.1 g/mol).
C7H6O3(s) + C4H6O3(l) C9H8O4(s) + C2H4O2(l)
If 2.04 g of C9H8O4 (M = 180.2 g/mol) is produced from the reaction of 3.00 g C7H6O3 and 5.40 g C4H6O3, what is the percent yield?
 a. 14.2% b. 21.4% c. 24.3% d. 52.1% e. 68.0%