Question

Question #c5bf1

Answer 1

You divide the moles of each substance by its coefficient of the balanced equation. The substance that has the smallest answer is the limiting reactant.

Consider the reaction:
2Al + 3I₂ → 2AlI₃

What is the limiting reactant if 1.20 g Al reacts with 2.40 g I₂?

Step 1: Convert all masses into moles.

1.20 g Al × `(1 mol Al)/(26.98 g Al)` = 0.0445 mol Al

2.40 g I₂ × `(1 mol I₂)/(253.8 g I₂)` = 0.009 46 mol I₂

Step 2: Divide the moles of each substance by its coefficient in the balanced equation.

For Al: 0.0445/2 = 0.0222

For I₂: 0.00946/3 = 0.003 15

Since I₂ gives the smaller number, I₂ is the limiting reactant.

Here is a video which discusses how to determine limiting reactants.

video from: Noel Pauller