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I have no idea about the 0.099 but i just wanted to point out that the number of moles of Cu is the number of moles of electrons divided by 2, since ech Cu atom takes 2 electrons, Cu2+(aq) + 2e- => Cu(s)
thats the confusing part!! I think the way he calculated the number of moles is wrong... but not sure... i need to do some research and ill get back to you.
stratomaster

Cathode: 13.44g (start), 14g (after) = +0.56g
Anode: 14.01 (start), 13.499 (after) = -0.511g

Current = 0.085A
Time = 9:50

Electric charge = current * Time(s)
= 0.085 * 590
= 50.15 C

1 mol of electrons = 96,486 C
Moles of electrons = 1/96,486 * 50.15 = 5.2*10^-4

5.2*10^-4/2 = 2.6*10^-4

molar mass Cu= mass/moles
=0.099 (where did he get this from?) / 2.6*10^-4
=380.8


if I assusme that the time is 9 minutes 50 seconds then the answer comes to:

2.6 x 10^-4 moles = 0.56g
1 mole = 2155 g which is clearly wrong!

If the time means 9 hours and 50 minutes then:

35400 x 0.085 = 3009 C
moles e = 3009/96486 = 0.0156/2 moles copper =0.0156
equivalent to 0.56g therefore 1 mole = 35.9

not much better but at least in the ball park...

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