# Need help. With Thermo

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

2Cu+(aq) → Cu + Cu2+(aq) ΔrH = ????

AGNuke
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

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.