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Homework Help: Electrolytic Cell

  1. Aug 7, 2010 #1
    "bar of gold or copper placed in acidic solution, attached via battery to item to be plated. Eyeglasses plated placed in solution, voltage applied to create electrolytic cell, which plates material."
    1. Total amount of gold to deposit on glasses made of aluminum = 0.5g. How long should the plating process be performed to deposit this amount of gold?
    2. If the glasses are plated with copper instead of gold...
    A) Reaction require lower V, proceed at same speed for equal current
    B) Reaction require lower V, but proceed more quickly
    C) Reaction require same voltage but proceed slowly for equal current

    Reduction potentials:
    Au3+ + 3e --> Au 1.5V
    Cu2+ + 2e --> Cu 0.34V
    Al3+ + 3e --> Al 1.66V

    1. 0.5g x (1mol/197gAu) x (3e-/1mole) x (96487C/mole) x 1s/C = ~730s
    However, answer is 73s because the last term they did is 1s/10C. How come?

    2. I was thinking that the reaction would require a higher voltage since the difference between the reduction potential of Al and Cu is greater than the difference between Al and Au.

    Thank you.
  2. jcsd
  3. Aug 7, 2010 #2
    What is the applied voltage? and that should explain the /[C] question
  4. Aug 8, 2010 #3
    The question actually doesn't mention anything about the applied voltage... at least I dont see it.
  5. Aug 9, 2010 #4
    It only says "A voltage is applied to create an electrolytic cell, which plates the material onto the eyeglass frames."
  6. Aug 9, 2010 #5
    The amount of plating depends on how much current is flowing which depends on the applied voltage(source). You need more information.
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