Copper sulphate solution `(250 ML)` was electrolyzed using a platinum anode and a copper cathode. A constant current of `2mA` was passed for `16 mi n`. It was found that after electrolysis the absorbance of the solution was reducted to `50%` of its original value . Calculate the concentration of copper sulphate in the solution to begin with.

Explanation

Number of faraday passed through the aqueous solution of `CuSO_(4)`
`=(Ixxt)/(96500)=((2xx10^(-3))xx16xx60)/(96500)=1.98xx10^(-5)`
Thus, number of equivalent of `CuSO_(4)` involved in electrolysis from 1 litre solution
`=4xx1.98xx10^(-5)=7.92xx10^(-5)`
Since, after electrolysis, the absorbance reduces to 50% hence, initial number of equivalent of `CuSO_(4)` per litre
`=2xx7.92xx10^(-5)`
`=1.584xx10^(-4)`
or Normality of `CuSO_(4)` solution `=1.584xx10^(-4) N`.