Reaction Stoichiometry II
Extra Stoichiometry Study Questions
1. a. What quantity, in moles, of water are formed by the reaction of 0.112 mol of oxygen gas with
excess hydrogen gas?
2 H2(g) + O2(g) → 2 H2O(g)
nH 2O = 0.112 mol O 2 ×
2 mol H 2 O
= 0.224 mol H 2 O
1 mol O 2
b. In the same reaction as above, what quantity in moles of hydrogen gas are consumed? (Just for
fun... how many molecules of hydrogen gas were consumed?)
nH 2 consumed = 0.112 mol O 2 ×
2 mol H 2
= 0.224 mol H 2
1 mol O 2
N H 2 consumed = 0.224 mol H 2 × 6.022 × 1023
molecules
mol
= 1.35 × 1023 molecules H 2
c. If 1.000 mol of hydrogen gas was available, how much remains?
nH 2 remaining = 1.000 mol − 0.224 mol = 0.776 mol H 2 remaining
2. The reaction of silver nitrate with potassium chloride yields silver chloride as one of the products.
What mass, in grams, of silver chloride will be produced by the reaction of 1.00 g of silver nitrate
with 0.439 g of potassium chloride?
AgNO3 + KCl → AgCl + KNO3
M AgNO3 = 169.9 g mol
M AgCl = 143.32 g mol
M KCl = 74.55 g mol
1.00 g AgNO3
 1 mol AgCl
= 5.886 × 10−3 mol AgCl
nAgCl from AgNO3 = 
g AgNO3
×
169.9
mol AgNO3  1 mol AgNO 3

(
nAgCl from KCl = 0.439 g KCl
74.55 g KCl mol KCl
AgCl
= 5.889 × 10
) × 11mol
mol KCl
AgNO3 is limiting reactant (but just barely)...
g AgCl
mAgCl = 5.886 × 10−3 mol AgCl × 143.32 mol
AgCl = 0.844 g AgCl
−3
mol AgCl
3. Assume that gasoline is entirely C7H8 (toluene). What mass of CO2 will be produced by burning 1
tank (48.0 L) of gasoline in your car? The density of toluene is 0.866 g/mL. (FYI, gasoline is an
enormously complex mixture of aliphatic and aromatic hydrocarbons with the toluene being a
major component.)
C7H8 + 9 O2 → 7 CO2 + 4 H2O
M C7 H8 = 92.141 g mol
mtoluene = 48, 000 mL × 0.866 g mL = 41,568 g toluene
mCO2 = 41,568 g C7 H8 ×
1 mol C7 H8
7 mol CO 2
×
× 40.01 g CO2 mol CO2
92.141 g C7 H8 1 mol C7 H8
mCO2 = 126,349 g CO 2 = 126, 000 g CO 2 = 1.26 ×105 g CO 2