doubt on molarity

a zinc rod weighing 25g was kept in 100ml of 1 M CuSO4 solution. after a certain time the molarity of Cu2+ in the solution was 0.8 M. the weight of zinc rod left is equal to

(A) 1.308 g
(B) 23.692 g
(C) 25g
(D) none of these

2 Answers

Ashish Kothari ·

Without putting much thought into this, the answer seems to be (B).

Ashish Kothari ·

This is what comes to my mind:

No. of moles of Cu2+ reduced to Cu = 0.1(1 - 0.8)=0.02

Therefore, weight of Zn oxidised = 0.02*65.4 = 1.308

Weight of Zinc rod left = 25 - 1.308 = 23.692 g

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