Stoichiometry 4
1. Consider the reaction: 2 KBr + Cl2  2 KCl + Br2.
If 4.5 g of KBr is reacted in excess chlorine, what mass of Br2 could be produced?
2. Calculate the mass in grams of elemental iodine that will react completely with 20.4 g of aluminum metal to
form aluminum iodide.
3. Hydrogen fluoride is used in the manufacture of Freons (which destroy ozone in the stratosphere) and in the
production of aluminum metal. It is prepared by the reaction
CaF2 + H2SO4  CaSO4 + 2 HF
In an industrial process 6.00 kg of CaF2 are treated with an excess of H2SO4 and yield 2.86 kg of HF.
Calculate the percent yield of HF.
4. If a solution containing 10.0 g of zinc chloride is mixed with a solution containing 15.0 g sodium phosphate,
what mass of precipitate zinc phosphate precipitate could be formed?
5. Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus
decaoxide and water.
4 PH3(g) + 3 O2(g) → P4O10(s) + 6 H2O(g)
Calculate the mass of PH3 required to react with excess oxygen and to produce 575 g of tetraphosphorus
decaoxide.
6. How many atoms of magnesium will react with 4.5 g of nitrogen to make magnesium nitride (Mg3N2)?
7. Iron metal reacts with oxygen to make iron (III) oxide by the following reaction:
4 Fe + 3 O2  2 Fe2O3
If 72.0 g of iron and 67.0 g of oxygen are present initially,
A) What is the limiting reagent?
B) What mass of iron(III) oxide is produced?
C) What mass of the excess reagent remains at the end of the reaction?