The drain cleaner, Drainex contains small bits of aluminum 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 aluminum reacts ?

Explanation

Reaction of Aluminium with caustic soda
`2Al_((s))+2NaOH_((aq))+H_(2)O_((l))to 2NaAlO_((aq))+3H_(2(g))`
`therefore 3` moles `H_(2)` is obtained from
2 moles Auminium
2 moles Aluminium = 3 moles `H_(2)` of STP. In experiment
where, `T=20^(@)C=(20+273)+293 K`
`R=8.314xx10^(-2)` L bar `K^(-1)mol^(-1)`
P = 1 bar, V = (?)
Weight of Al = 0.15 g and Mole of `Al = (0.15)/(27)`
According to reaction equation.
3 moles `H_(2)` is obtasined form 2 moles Al n moles `H_(2)` is obtained
from `(0.15)/(27)` Al.
`therefore n = (3 mol H_(2)xx 0.15 "mol Al")/("2 mol Al"xx27)`
`=0.000833=8.33xx10^(-3)` mole `H_(2)` gas
pV = nRT and
`V=(nRT)/(p)`
`= ((8.333xx10^(-3)mol)(8.314xx10^(-2)"L bar mol"^(-1)K^(-1))(293 KJ))/("1 bar")`
`= 20291.897xx10^(-5)L`
`= 2.0291xx10^(-1)L=0.2029L=202.9 mL ~~ 203 mL`