In: Chemistry
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.
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