Question

The drain cleaner, Drainex contains small bits of aluminum which react with caustic soda to produce dihydrogen. What volume of dihydrogen at $20{}^{\circ }C$ and one bar will be released when $0.15g$ of aluminum reacts?

Answer 1

The balanced chemical equation is $2Al+2NaOH+2H_{2}O\to 2NaAl{O}_2+3H_2$.
54 g (2 mol) of Al will give 3 moles (or 67.2 L) of hydrogen.
0.15 g of Al will give $\frac{67.2}{54}\times 0.15=0.189L$ of hydrogen.
The volume of hydrogen is at 1 bar and 273 K. The volume at 1 bar and ${20}^{0}C$ will be, $V^{\prime }=\frac{PV{T}^{\prime }}{P^{\prime }T}=\frac{1\times 0.189\times 293}{1\times 273}=0.2028L=202.8ml$.