Notes - limiting reagents

Limiting Reactant

• limiting reactant controls the amount of product that is formed in a chemical reaction
• How do you calculate limiting reactant?

1) If necessary, convert reactants A & B to moles
2) Using the # of moles given for A, calculate how many moles of B would be needed to react.
3) Using the # of moles given for B, calculate how many moles of A would be needed to react.
4) Which reactant will you run out of first (the one where your NEED

exceeds what you are GIVEN)? This is your limiting reactant.

SiO₂(s) + 4HF(g) ? SiF₄(g) + 2H₂O(l)

If 2.0 mol of HF is combined with 4.5 mol SiO₂, which is the limiting reactant?

N₂H₄(l) + 2H₂O₂(l) ? N₂(g) + 4H₂O(g) (propellants used in some rockets)

What is the limiting reactant when 24.0 g of N₂H₄ reacts with 17.0 g of H₂O₂?

How many grams of excess reactant remain?

How many grams of water vapor are produced?

1. You synthesize 50.0 g of sodium with 60.0 g chlorine gas to produce table salt. Please identify your limiting reactant and your excess reactant.

2. In a single replacement reaction between 50.0 g of zinc and 30.0 g of hydrochloric acid. What is your limiting reactant? How many grams of zinc chloride is produced? 3. 40.0 g of sodium iodide are combined with 50.0 g of silver nitrate. What is the limiting reactant? How many formula units of sodium nitrate are produced?