Copper sulphate solution (250 mL) was electrolysed using a platinum anode and a copper cathode. A constant current of 2 mA was passed for 16 min . It was found that after electrolysis the absorbance of the solution was reduced to 50% of its original value. Concentration of copper sulphate in the solution to begin with is x × 10 - 5 . Find the valu of x

Step-by-step solution

The number of faraday's passed = 2 × 1 0 - 3 × 1 6 × 6 0 9 6 5 0 0 = 1.99 × 1 0 - 5 ⇒ number of gram equivalent of Cu 2 + deposited as Cu(s) = 1.99 × 1 0 - 5 ⇒ number of moles of Cu 2 + deposited = 1.99 2 × 10 - 5 ≈ 10 - 5 Absorbance is directly proportional to Cu 2 + . No. of moles of Cu 2 + initially present = 2 x 10 -5 moles Cu 2 + Initial = 2 × 1 0 - 5 × 1 0 0 0 2 5 0 = 8 x10 -5 M