Chem 101 Weekly Worksheet Stoichiometry

1. Given the following equation: 2 KClO3 ---> 2 KCl + 3 O2

How many moles of O2 can be produced by reacting 12.24 moles of KClO3?

2. Given the following equation: 2 K + Cl2 ---> 2 KCl How many grams of KCl are produced from 2.50 g of K and excess Cl2?

How many grams of KCl are produced from 1.00 g of Cl2 and excess K?

3. Given the following equation: Na2O + H2O ---> 2 NaOH

How many grams of NaOH is produced from 1.20 x 102 grams of Na2O?

How many grams of Na2O are required to produce 1.60 x 102 grams of NaOH?

4. Given the following equation: 8 Fe + S8 ---> 8 FeS

What mass (in g) of iron is needed to react with 16.0 grams of sulfur?

How many grams of FeS are possibly produced (What is the theoretical yield)?

5. How much (in grams) magnesium hydroxide do you need to use in the below reaction to produce 500 grams of ammonia?

Mg(OH)2 + (NH4)2 SO4 2H2O + MgSO4 + 2NH3

GIVEN: 500 grams of ammonia gas (NH3)

FIND: mass of magnesium hydroxide (Mg(OH)2).

If the reaction started with 2000 grams of (NH4)2SO4 with excess Mg(OH)2 and you still recovered 500 g of Ammonia. What is the percent yield? 

6. Try solving the following equation using both of the methods above.

Mg(OH)2 + (NH4)2 SO4 2H2O + MgSO4 + 2NH3

What is the limiting reagent if you are given 227 g of Mg(OH)2 (Mol. weight of Mg(OH)2 is 58.305 g/mole) and 325 g of (NH4)2SO4 (Mol. weight of (NH4)2SO4 is 132 g/mole).

7. Given the following reaction:

2 FeCl3 + 3 H2S à 1 Fe2S3 + 6 HCl 90.0 g of FeCl3 reacts with 52.0 g of H2S.

What is the limiting reactant?

What is the mass of HCl produced?

What mass of excess reactant remains after the reaction?

NOTE: The limiting reactant is the reactant that limits the amount of product that can be formed and is completely consumed during the reaction. The excess reactant is the reactant that is left over once the reaction has stopped due to the limiting reactant.