Question

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

Answer 1

Solution:-

The balanced reaction is-

$2Al+2NaOH+2H_{2}O⟶2NaAl{O}_2+3H_2$

At STP:

2 moles of aluminium reacts to form 3 moles of dihydrogen, i.e., 54g of aluminium reacts to form 67200 mL$(22400\times 3)$ of dihydrogen.

$\therefore$ 0.15 g of aluminium gives 186.67 mL $(\frac{67200}{54}\times 0.15)$ of dihydrogen

At STP:

$P_1=1atm$

$V_1=186.67mL$

$T_1=273K$

Let the volume of hydrogen be $V_2=V$ at:

$P_2=1bar=0.0987atm$

$T_2=20℃=293K$

As we know that,

$\frac{P_1{V}_1}{T_1}=\frac{P_2{V}_2}{T_2}$

$\therefore \frac{1\times 186.67}{273}=\frac{0.987\times V}{293}$

$\Rightarrow V=\frac{186.67\times 293}{273\times 0.0987}=202.98\approx 203mL$