# What volume of hydrogen at STP is produced when 2.5 g of zinc react with an excess of hydrochloric acid in the reaction Zn + 2HCl -> ZnCl_2 + H_2?

Feb 28, 2016

$0.86 \text{L}$

#### Explanation:

$1 \text{mol}$ of $\text{Zn}$ has mass of $65.39 \text{g}$.

The amount of $\text{Zn}$ is frac{2.5 "g"}{65.39 "g/mol"} = 0.038 "mol".

The amount of ${\text{H}}_{2}$ produced is the same as the amount of $\text{Zn}$ consumed $\left(0.038 \text{mol}\right)$.

$1 \text{mol}$ of ideal gas will occupy $22.4 \text{L}$ at STP.

The ${\text{H}}_{2}$ will occupy $0.038 \text{mol" xx 22.4 "L/mol" = 0.86 "L}$.