In a laboratory, 8.0 g of zinc metal reacts completely with excess hydrochloric acid. Find the mass of hydrogen gas produced.

Step-by-step solution

1. Write the balanced equation: $\mathrm{Zn}+2HCl\to \mathrm{ZnC}{\mathrm{l}}_2+{\mathrm{H}}_2$.
2. Calculate moles of Zn: $\frac{8.0\mathrm{g}}{65.38\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}}=0.1225\mathrm{mol}$.
3. Moles of H₂ produced equal moles of Zn: 0.1225 mol.
4. Mass of H₂ = 0.1225 mol × 2.02 g mol⁻¹ = 0.245 g.

Concept tested: Stoichiometry of metal‑acid reaction

Published 10 October 2026 · How this solution was prepared and checked