The drain cleaner, Drainex contains small bits of aluminium which react with caustic soda to produce dihydrogen. What volume of dihydrogen in mL at 20 ° C and one bar will be released when 0.15 g of aluminium reacts?

Question

Quantrex Academy · Accepted Answer

Correct answer: 203

The reaction between aluminium and caustic soda is

\mathop{2Al}_{\mathop{2 \times 27}_{= 54g}} + 2NaOH + 2{H}_{2}O \to 2NaAl{O}_{2} + \mathop{3{H}_{2}}_{\mathop{3 \times 22.4L}_{\text{atSTP}}}

So 54 g of Al produces

{H}_{2}

at STP

= 3 \times 22.4

L
0.15 g of Al will produce

{H}_{2}

at STP

= \dfrac{3 \times 22.4}{54} \times 0.15

= 0.186L

At STP	Given Conditions
${P}_{1} = 1$ atm	${P}_{2} = 1$ bar $= 0.987$ atm
${V}_{1} = 0.186$ L	${V}_{2} = ?$
${T}_{1} = 273$ K	${T}_{2} = 273 + 20 = 293K$

Applying ideal gas equation,

\dfrac{{P}_{1}{V}_{1}}{{T}_{1}} = \dfrac{{P}_{2}{V}_{2}}{{T}_{2}}

\dfrac{1 \times 0.1867}{273} = \dfrac{0.987 \times {V}_{2}}{293}

{V}_{2} = \dfrac{293}{0.987} \times \dfrac{1 \times 0.1867}{273}

= 0.2030

L

= 203

mL

The drain cleaner, Drainex contains small bits of aluminium which...

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