Based on the following reaction 2A + 3B --> A2B3, if 1 mole of A is reacted with 2 moles of B, explain how you would determine which of the two substances is the limiting reactant.

Answer 1

2A + 3B ==> A2B3

1 mol A x (1 mol A2B3/2mols A) = 1 x 1/2 = 1/2 mol A2B3 formed.

2mols B x (1 mol A2B3/3mols B) = 2 x 1/3 = 2/3 mol A2B3 formed.
In limiting reagent problems, the SMALLER number is ALWAYS the correct value and the reagent producing that number is the limiting reagent. So which is smaller, 1/2 or 2/3.