Question

In: Chemistry

When molten zinc chloride (ZnCl2) is electrolyzed, zinc is deposited at the cathode. Calculate the amount...

When molten zinc chloride (ZnCl2) is electrolyzed, zinc is deposited at the cathode. Calculate the amount of zinc produced if a current of 12.2 A is passed through the electrolytic cell for 45.3 min.

THEN

A metal bromide, MBr2, is converted to a molten form at high temperature. Electrolysis of this sample with a current of 6.23 A for 73.2 seconds results in deposition of 0.266 g of metal M at the cathode. The other product is bromine gas, Br2(g), which is released at the anode. Determine the identity of metal M.

Solutions

Expert Solution

Question 1.

t = 45.3 min = 45.3*60 = 2718 seconds

Total charge:

I = C/t

C = I*t = (12.2)(2718) = 33159.6 C

change to mol of e-

1 mol of e- = 96500 C

x mol = 33159.6 C

x = 33159.6/96500 = 0.343622 mol of e-

note taht

1 mol of Zn = 2 mol of e- required

0.343622 mol of e- --> !/2*0.343622 = 0.171811 mol of ZN

mass = mol*Mw = 0.171811*65.38 = 11.23300 g of Zn

PART 2:

MBr2 <-> M+2 + 2Br-

total charge = 6.23*73.2 = 456.036 C

mol of e- = 456.036/96500 = 0.00472 mol of e-

mol of M+2 = 1/2*0.00472 = 0.00236 mol of M+2

MW = mass/mol = 0.266/0.00236 = 112.71 g/mol

MW of Cd = 112.1 g/mo, this must be Cadmium, Cd


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