HSC 2008 question 25 help please

[howlc]

You can hide this advertisement by registering.

So i know
reduction occurs at the cathode
and oxidation at the annode

but the question says

Ni (electrode) is in Ni(NO3)2 aq
and
Pt (electrode) is in KCl aq (Cl2 gas is being put in)

i went to the standard potentials but cant seem to work out which is the annode and which is the cathode? help please

if its easier simple just answer the actual question on the paper =]

[luvakuma]

Ni is on top of Pb on the standard potentials, so the reaction for nickel has to go from solid to ions, for there to be any voltages coming out
Pb gains electrons, (OIL RIG) so reduction
and Ni loses electrons, so oxidation

Pb is the cathode
and Ni is the anode

I hope...

[Pwnage101]

lol ^^^ where di u get Pb from?

its a PLATINUM (PT) electrode - we use that when we are dealing with gases (such as CL2 in this case) to provide a surface for teh redox reaction to occur on - we need an inert metal - and thats why Pt is used.

so u are dealing with Cl2(g) and Ni(s) in this case [both are on the stanrad reduction potentials table = HINT do not confuse Cl2 (g) with Cl2 (aq), not that it matters in this case]

Which is reduced and which is oxidised? hence which one is the anode/cathode?

if u cant find the answer aafter thinking about it a bit, post bak with wat u have so far and we'll help out some more.

[howlc]

Thanks for help guys i managed to work it out =]