Question

1.How many coulombs are required to produce 47.9 g of cobalt metal from a solution of aqueous cobalt (III)chloride Use scientific (E) notation with 2 numbers after the decimal point.

2.How many grams of chromium may be formed by the passage of 95,469 C through an electrolytic cell that contains an aqueous Cr(IV) salt.

3.What product(s) forms at the anode in the electrolysis of an aqueous solution of SnSO₄?

Answer 1

1.

Cr+3    + 3e- -----------------------------> Cr

3 mol of electrons are needed

that means 3 F are required

3 F---------------------> 51.996 g Cr deposited

x F --------------------> 47.9 g Cr deposited

x = 3 x 47.9 / 51.996 = 2.76 F

1 F = 96485 C

2.76 F = 2.76 x 96485 C = 266653 C

2.67 E^5 C are required

2.)

Cr+4 + 4e -------------------> Cr

4 x 96485 C -----------------> 51.996 g

95,469 C -----------------------> x g

x = 12.862 g

Cr formed = 12.862 g

3.What product(s) forms at the anode in the electrolysis of an aqueous solution of SnSO₄?

H2O --------------------------> H+   + OH-

SnSO4-------------------------> Sn+2   + SO4-2

H+ deposition potential lesser than Sn+2 . so   H+ discharge first

at cathode : H2 gas formed

now OH- and SO4-2 ions compitation.

OH- discharge potential is lesser than SO4-2 so it gives O2 at anode

at anode product: O2 ,