Two electrolytic cells containing silver nitrate solution and dilute sulphuric acid solution were connected in series. A steady current of 2.5 amp was passed through them till 1.078 g of silver was deposited. [Ag=107.8 g `mol^(-1)`,1 F=96,500 C]
(i) How much electricity was consumed ?
(ii) What was the weight of oxygen gas liberated ?

Answer

(i) 965 C (ii) 0.16g

Explanation

(i) `Ag^(+)+etoAg, 1 mol (107.8g)` are deposited by 1F `therefore1.078` will be deposited by 0.01 F=965C
(ii) `2H_(2)Oto4H^(+)+O_(2)+4e^(-)` on each electrode
4F liberated 32g `O_(2) therefore0.01F` will liberate `O_(2)=0.08g`
`O_(2)` liberated on both electrodes=`=2xx0.08g=0.16`g.