(a) Give reasons for the following (i) Rusting of iron is quicker in saline water than in ordinary water. (ii) Aluminium metal cannot be prodcued by the electrolysis of aqueous solution of aluminium salt. (b) Resistance of a conductivity cell filled with 0.1 M KCl solution is 100 ohms. If the resistance of the same cell when filled with 0.02 M KCl solution is 520 ohms, calculate the conductivity and molar conductivity of 0.02 M KCl solution. Conductivityof 0.01 M KCl solution is 1.29 S m^(-1).

(a) Give reasons for the following (i) Rusting of iron is quicker in

1.	(a) Give reasons for the following (i) Rusting of iron is quicker in saline water than in ordinary water. (ii) Aluminium metal cannot be prodcued by the electrolysis of aqueous solution of aluminium salt. (b) Resistance of a conductivity cell filled with 0.1 M KCl solution is 100 ohms. If the resistance of the same cell when filled with 0.02 M KCl solution is 520 ohms, calculate the conductivity and molar conductivity of 0.02 M KCl solution. Conductivityof 0.01 M KCl solution is 1.29 S m^(-1).
Answer» Solution :(a) (i) It is because in saline water, there are more `H^+ ` ions . Greater the number of `H^+` ions, quicker the rusting will take place. (ii) It is because ALUMINIUM metal is more REACTIVE than hydrogen and it will react with `H_2O`. (b) CELL constant = Conductivity (k) `xx` Resistance (R) `= 1.29 S m^(-1) xx 100 OMEGA` `= 129 m^(-1) = 1.29 cm^(-1)` `lambda_m = (100 k)/M` `k = 1/R xx l/A ` `k= 1/(520 Omega) xx 1.29 cm^(-1)`, where `l/A =` cell constant `:. k = 2.48 xx 10^(-3) S cm^(-1)` `lambda_m = (100 xx 0.248 xx 10^(-2))/(0.02)` `= 124 S cm^(-2) mol^(-1)`.