0.10g of a sample containing CuCO3 and some inert impurity was dissolved in dilute sulphuric acid and volume made up to 50 ml. This solution was added into 50 ml of 0.04 M KI solution where copper pre

Question

0.10g of a sample containing CuCO3 and some inert impurity was dissolved in dilute sulphuric acid and volume made up to 50 ml. This solution was added into 50 ml of 0.04 M KI solution where copper precipitates as CuI and I– is oxidised into 3I. A 10 ml portion of this solution is taken for analysis filtered and made up free 3I and then treated with excess of acidic permanganate solution. Liberated iodine required 20 ml of 2.5 mM sodium thiosulphate solution to reach the end point. Determine the wt. percentage of CuCo3 in the original sample.

(A) 7.41
(B) 74.1
(C) 61.75
(D) None of these

Prashant Kotian · Accepted Answer

Correct answer:

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