Question

The Cu-Zn cell (Zn|Zn2+||Cu2+|Cu) is called a Daniel cell. If it initially has 10.0g of Zn and 10.0g of Cu and 100ml each of .500M CuSO4 and ZnSO4, for how long can it go given a current of 25.0 mA?

Answer 1

The moles of copper = Mass of copper / Atomic weight of copper = 10 / 63. 5 = 0.157 moles

the moles of zinc = Mass of zinc / atomic weight of zinc = 10 / 65.38 = 0.152 moles

so moles of Zn = moles of copper deposited = 0.152 moles

Gram equivalents of copper = 0.076

1F is required to deposit 1 gequivalent

so faradays required =0.076 F = 96485.3 X 0.076 coloumbs = 7332.8 coloumbs

Current = charge / time

Time = Charge / current = 7332.8 / 25 milliamperes = 293.312 seconds = 81.47 hours