Question #659e3

Sep 24, 2014

Three steps:
(1) Write the balanced chemical equation;
(2) Use the molar mass to convert grams of Al to moles of Al;
(3) Use the molar ratio of Al:I₂ to get the moles of I₂.

Step 1. Write the balanced chemical equation.

2Al + 3I₂ → Al₂I₆

Step 2. Convert mass of Al → moles of Al

Moles of Al = $\text{10.0 g Al" × "1 mol Al"/"26.98 g Al" = "0.3706 mol Al}$ (3 significant figures + 1 guard digit)

Step 3. Convert moles of Al →moles of I₂

The molar ratio of Al:I₂ = 2:3

Moles of I₂ = ${\text{0.3706 mol Al" × ("3 mol I"_2)/"2 mol Al" = "0.556 mol I}}_{2}$