# Percentage Yield

```Name__________________________________Period_______Date_________
Percentage Yield
Directions: Answer each of the following questions. You will need to use your periodic
table. Example calculations are in section 9.3 of your textbook.
1. Methyl alcohol, CH3OH, is used as a fuel in alcohol-burning race cars. It can be
manufactured according to the following reaction:
2H2(g) + CO(g) → CH3OH(l)
When 34.5 g of hydrogen gas reacts with excess carbon monoxide gas, the actual
yield of methyl alcohol is 252.2 g. What is the percentage yield of methyl alcohol?
2. Milk of magnesia is used as an antacid. It is an aqueous suspension of magnesium
hydroxide, a mild base. It acts in the stomach according to the following reaction:
Mg(OH)2(s) + 2HCl(aq) → 2H2O(l) + MgCl2(aq)
When 28.0 g of magnesium hydroxide react with excess hydrochloric acid solution in
an experiment to simulate the action of magnesium hydroxide in the stomach, the
actual yield of magnesium chloride is 35.8 g. What is the percentage yield of
magnesium chloride?
3. Hydrogen cyanide gas is produced by reacting ammonia gas, oxygen gas, and
methane gas according to the following reaction:
2NH3(g) + 3O2(g) + 2CH4(g) → 2HCN(g) + 6H2O(g)
If the typical yield is 89.8%, what mass of hydrogen cyanide gas should be expected
if 324 g of ammonia gas are reacted with excess oxygen gas and methane gas?
4. The fuel used in the booster rockets attached to the space shuttle contains a mixture
of aluminum and ammonium perchlorate. The following equation represents one
proposed reaction for the “burning” of this fuel:
3Al(s) + 3NH4ClO4(s) → Al2O3(s) + AlCl3(s) + 6H2O(g) + 3NO(g)
If the typical yield is 83.4%, what mass of aluminum chloride should be expected if
3.50 kg of aluminum are reacted with excess ammonium perchlorate?
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