Chapter 9 Stoichiometry: Practice Test
3/29/2006 9:20:18 AM
Solve the following problems in the space provided. Show your work.
1) a. What is the limiting reagent when 50.2 g of nitrogen react with 10.7 g of
hydrogen according to this balanced equation?
b. What mass of ammonia would be produced?
N2(g) + 3H2(g)  2NH3(g)
2) How many grams of CO are needed to react with an excess of Fe2O3 to produce 558 g
of Fe? The unbalanced equation for the equation is:
Fe2O3(s) +
CO(g) 
CO2(g) +
Fe(s)
3) How many grams of butane (C4H10) must be burned in an excess of O2 to produce
15.0 g of CO2?
2C4H10(g) + 13O2(g)  8CO2(g) + 10H2O(g)
4) a. If 4.0 g of H2 are made to react with excess CO, how many grams of CH3OH can
theoretically be produced according to the following equation?
CO(g) + 2H2(g)  CH3OH(l)
b. If 28.0 g of CH3OH are actually produced, what is the percent yield?
5) A 5.00 x 102 g sample of Al2(SO4)3 is made to react with 450 g of Ca(OH)2. A total of 596 g
of CaSO4 is produced. The balanced equation is:
Al2(SO4)3(aq) + 3Ca(OH)2(aq)  2Al(OH)3(s) + 3CaSO4(s)
a. What is the limiting reagent in this reaction?
b. How many grams of excess reagent are unreacted?
6) How many grams of O2 are needed to react completely with 15.2 g of H2S according
to the following unbalanced equation?
H2S(g) +
O2 
SO2(g) +
H2O(g)
7) The decomposition of potassium chlorate gives oxygen gas according to the reaction:
2KClO3(s)  2KCl(s) + 3O2(g)
How many grams KClO3 are needed to produce 7.14 g of O2?
8) Suppose that the reaction described in question 7 produces 6.86 g of O2 in the
laboratory. What is the percent yield?
Answers:
1) [H2 is limiting]
[ 60.3 g NH3]
2) [420. g CO]
3) [4.94 g C4H10]
4) [32.0 g CH3OH]
[ 87.5 %]
5) [Al2(SO4)3]
[125g excess Ca(OH)2]
6) [21.4 g O2]
7) [18.2 g ClO3]
8] [96% yield]