Limiting Reactants

For each of the following problems, you are to identify the limiting reactant after showing all work to indicate how you arrived at your answer.

1. Some propellants for rockets use the following reaction:

N₂H₄ + 2 H₂O₂ ---> N₂ + 4 H₂O

What is the limiting reactant when 0.750 mol of N₂H₄ is mixed with 0.500 mole of H₂O₂?

Answer: H₂O₂

2. For the reaction

2 Na + Cl₂ ---> 2 NaCl

If 20.5 g of chlorine is reacted with 20.5 g of sodium, which reactant is in excess?

Answer: Sodium

3. For the reaction 8 Zn + S₈ ---> 8 ZnS,

if 2.00 mol of Zn are heated with 1.00 mol of S₈ identify the limiting reactant.

Answer: Zn

4. For the reaction,

C + H₂O ---> H₂ + CO

if 2.40 mol of carbon are reacted with 3.10 mol of water, identify the limiting reactant.

Answer: carbon

5. For the reaction,

CS₂ + 3 O₂ ----> CO₂ + 2 SO₂

a) if 1.00 mol of carbon disulfide is combined with 1.00 mol of oxygen, identify the limiting reactant.

Answer: oxygen

b) How many moles of excess reactant remain?

Answer: 0.667 mol carbon disulfide

6. For the reaction,

Mg + 2 H₂O ---> Mg(OH)₂ + H₂

if 16.2 g of magnesium are heated with 12.0 g of water, what is the limiting reactant?

Answer: water

How many grams of excess reactant are left?

Answer: 0.333 mol magnesium