3.2.4 Limiting Reactants

• What does it mean for a reactant to be a 'limiting reactant'?

  It all reacts and limits how much product can be formed.
• If 4g of calcium reacts with oxygen from the air, which is most likely to be a limiting reactant, the calcium or the oxygen? 

  Calcium.
• CaO + H2O ➔ Ca(OH)2

  Calcium oxide and water react in a 1: 1 ratio.

  In a reaction between 3 moles of calcium oxide and 7 moles of water, what is the limiting reactant?

  Calcium oxide.
• What does it mean for a reactant to be 'in excess'?

  It does not all react, and has no effect on the amount of product formed.
• 2SO2 + O2 ➔ 2SO3

  Sulfur dioxide and oxygen react together in a 2:1 ratio. In a reaction between 1.8 moles of sulfur dioxide, and 1 mole of oxygen, which reactant will be in excess?

  Oxygen.