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20   mL of 0 . 02   M hypo solution is used for the titration of 10   mL of copper sulphate solution, in the presence of excess of KI using starch as an indicator. The molarity of Cu 2 + is found to be _ _ _ _ _ × 10 - 2 M (nearest integer) Given : 2 Cu 2 + + 4 I - → Cu 2 I 2 + I 2 I 2   +   2 S 2 O 3 - 2     →     2 I —   +   S 4 O 6 - 2

Correct answer

0

Step-by-step solution

n eq . of I 2 = n eq of Na 2   S 2 O 3 = 20 × 0 . 02 × 10 - 3 2 × n mol of I 2 = 0 . 4   × 10 - 3 n mol of I 2 = 0 . 2   m   mol n mol of Cu + 2 = 0 . 2 × 2 × 10 - 3 Cu + 2 = 0 . 4 × 10 - 3 10 × 10 - 3 = 0 . 04 = 4 × 10 - 2

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