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A zinc-copper battery is constructed as follows at 25°C.

Zn|Zn^2+ (0.15 M)||Cu2+(3.00 M)|Cu

The mass of each electrode is 200. g.

a) Calculate the cell potential when this battery is first connected.
- i got this to be 1.14V

b.) Calculate the cell potential after 10.0 A of current has flowed for 10.0 h

(c) Calculate the mass of each electrode after 10.0 h.

d) How long can this battery deliver a current of 10.0 A before it goes dead?

please help! i just can't seem to figure out how to calculate the concentrations of the Zn^2+ and Cu^2+ after the current has flowed through.
-thanks.

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3 answers
  1. Do you have a volume?
    10A x 10hrs x 3600 s/hr = 36,000 coulombs.
    96m485 C will dissolve (or plate out) 1 equivalent weight of a metal.
    1 equivalent weight of Zn = 65.38/2 = 31.3
    1 equivalent weight of Cu = 63.55/2 = 31.8
    Zn dissolved = 31.2 x (36,000/96,485) = ??
    Cu plated = 31.8 x (36,000/96,485) = ??
    ?? grams of each can be converted to moles but we need a volume to convert to molarity. I don't see that in the problem.

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  2. yes, each half-cell contains 1.00 L of solution so that is the volume
    thank you!

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  3. 10A x 10hrs x 3600 s/hr = 36,000 coulombs.

    You forgot to multiply by 10A...it should be 360,000 coulombs. 36,000 is seconds in 10 hours.

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