Question

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

• A. $204 \,mL$
• B. $200 \,mL$
• C. $203 \,mL$
• D. $400 \,mL$

Answer 1

Answer: (C)

$203 \,mL$

Answer 2

The reaction between aluminium and caustic soda is $2Al + 2NaOH + 2H_2O ?$2 ? 27 = 54 ,g \quad 3 ? 22.4, L$at$STP$$\therefore 54 ,g$of$Al$produces$H_2$at$STP = 3 ? 22.4 L$$0.15, g$of Al will produce$H_2$at$STP$$=\frac{3\times22.4}{54}\times0.15=0.186,L$At$STP$Given conditions$P_{1}=1,atm,P_{2}=1,bar=0.987,atm$$V_{1}=0.186,L,V_{2}=?$$T_{1}=273,K,T_{2}=273+20=293,K$Applying ideal gas equation,$\frac{P_{1}V_{1}}{T_{1}}=\frac{P_{2}V_{2}}{T_{2}}$$\frac{1\times0.1867}{273}=\frac{0.987\times V_{2}}{293}$$V_{2}=\frac{293}{0.987}\times\frac{1\times0.1867}{273}=0.2030,L=203,mL$