1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Need help. With Thermo

  1. Sep 9, 2012 #1
    Hi, I have my exam in a couple of weeks. And I get the jist of it. However their is one question that I am completly stuck on. Any help would be appreciated.

    Looking over a last years practise text for exam and im having trouble with this.

    Cu(s) → Cu+(aq) + e ΔH = 602 kJ mol-1
    Cu(s) → Cu2+(aq) + 2e ΔH = 795 kJ mol-1
    Work out the Heat of Reaction for the following equation and comment on
    the expected stabilities of Cu+ and Cu2+ ions as predicted from your
    spdf answers in (d).

    2Cu+(aq) → Cu + Cu2+(aq) ΔrH = ????
  2. jcsd
  3. Sep 9, 2012 #2


    User Avatar
    Gold Member

    Try to break it into two equations. Cu+ to Cu2+ and Cu+ to Cu.

    For the first reaction, you can find its ΔH by subtracting the equations given in data. ΔH would be 193 KJmol-1
  4. Sep 13, 2012 #3
    Alternative approach, probably simpler:

    The problem you are having is that you do not have a half-reaction connecting Cu(+) and Cu(2+)

    So why not reduce both mole of Cu(+) to Cu, and couple it with oxidizing one mole of Cu all the way to Cu(2+)? That will balance the electrons, and produce the exact overall effect that you are wanting.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook