Question

a current of 1.5A was passed through an electrolytic cell containing dilute tetraoxosulphateVIacid for 40 minutes . calculate the volume of gas at s.t.p .(F=96500C ,GMV=22.4)

Answer 1

Total charge passed $=$ $Q=It=1.5\times 40\times 60=$ $3600C$

Now,

$m=\frac{MQ}{nF}$

Here,

$m=mass obtained$

$M=Molarmass$

Now, $No. of mole=$ $\frac{m}{M}=\frac{Q}{nF}$

$F=96500C$

equation for Hydrogen:

$2H^+(aq)+2e^-\to$ $H_2(g)$

$n=2$

Moles of hydrogen obtained$=\frac{Q}{nF}=\frac{3600}{2\times96500}=0.01865mole$

Volume of Hydrogen obtained$=0.01865\times22.4=0.418l$ $($Molar Volume at S.T.P. $=22.4l$ $)$

equation for Oxygen:

$4OH^-(aq)\to2H_2O(l)+4e^-$

$n=4$

Moles of Oxygen obtained$=\frac{Q}{nF}=$ $\frac{3600}{4\times96500}=0.00933mole$

Volume of Oxygen obtained $=0.00933\times 22.4=0.209l$

Total volume obtained$=$ Volume of Hydrogen $+$ Volume of Oxygen $=0.418+0.209=0.627l$