Question

Hydrogen gas can be produced in the laboratory through the reaction of hydrochloric acid with magnesium metal.
2HCl(aq)+Mg(s)→H2(g)+MgCl2(aq). When 12.5 g of Mg reacts, what volume, in liters, of H2 gas is produced at 22 ∘C and 809 mmHg?
Express your answer with the appropriate units.

Answer 1

Hydrogen gas can be produced in the laboratory through the reaction of hydrochloric acid with magnesium metal.

$2\mathrm{HCl(aq)} + \mathrm{Mg(s)} \rightarrow \mathrm{H2(g)} + \mathrm{MgCl2(aq)}$. When $12.5\mathrm{g}$ of Mg reacts, what volume, in liters, of H2 gas is produced at $22^{\circ}\mathrm{C}$ and $809\mathrm{mmHg}$?

Express your answer with the appropriate units.

$$P = 107,857 \text{ kPa}$$ $$T = 22 + 273 = 295 \text{ K}$$ $$n(\mathrm{H_2}) = n(\mathrm{Mg}) = 12.5\mathrm{g}/24\mathrm{g/mol} = 0.52\mathrm{mol}$$ $$\mathrm{PV} = nRT$$ $$V = nRT/P = 0.52\mathrm{mol} \times 8.31\mathrm{J/mol} \times K \times 295\mathrm{K} / 107857\mathrm{Pa} = 0.0118\mathrm{m^3} = 11.8\mathrm{L}$$

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