Answer to Question #331810 in Inorganic Chemistry for Philip

Question

If a given quantity of electricity liberates 0.65g of Zn2+, what amount of Hg2+ would be liberated by the same quantity of current?

[Zn = 65, Hg = 201]

A. 1.00g

B. 2.10g

C. 4.02g

D. 8.04g

Please show working

Answer 1

Zn²⁺_(aq) + 2e^- ----> Zn_(s)

                    1mol           2F            1mol

                     65g            2F             65g

From the above equation, 2F of electricity are needed to deposit 1 mole of zinc metal, and 1 mole of zinc = 65g.

If, 65g of zinc are deposited by 2F of electricity, then

0.65g of zinc will be deposited by x F of electricity

                               x = 0.65 x 2/65

                                  = 0.02F

For mercury, Hg;

                     Hg²⁺_(aq) + 2e^- ----> Hg_(l)

                     1mol           2F           1mol

                     201g           2F           201g

If, 2F of electricity deposit 201g of Hg

0.02F of electricity will deposit xg of Hg

                            x = 0.02 x 201/2

                               = 2.01g of Hg