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Pt (s)

Posted: Wed Feb 27, 2019 1:26 pm
by Mona El Masri 1F
Do we add Pt solid to reactions that contain a liquid as well, or only aqueous and gas?

Re: Pt (s)

Posted: Wed Feb 27, 2019 2:41 pm
by Ashley Zhu 1A
you do not need to add Pt(s) to liquids in cases where you have Hg(l) and Hg ions, but I am not sure if there are any exceptions/other cases

Re: Pt (s)

Posted: Wed Feb 27, 2019 3:11 pm
by Sophia Ding 1B
Why do you not need to add Pt(s) to liquids?

Re: Pt (s)

Posted: Wed Feb 27, 2019 3:16 pm
by Celine Hoh 2L
I think we also add Pt when both species of the same kind are in the same solution, say Fe2+ and Fe3+

Re: Pt (s)

Posted: Wed Feb 27, 2019 4:38 pm
by Arta Kasaeian 2C
We add Pt(s) to any side of the diagram (anode or cathode) that doesn't include a solid conductor within the reaction.

Re: Pt (s)

Posted: Wed Feb 27, 2019 5:53 pm
by Daisylookinland
In the homework problem 6L5 part b in the 7th edition, one of the cell diagrams is Pt(s)|I^-(aq)|I2(s)||Ce^4+(aq), Ce^3+(aq)|Pt(s)

I don't really understand why the Pt is included here, can someone explain?

Re: Pt (s)

Posted: Wed Feb 27, 2019 6:13 pm
by Kyleigh Follis 2H
Pt is included because in the cathode are two ion compounds in solution, so an inert electrode is needed.

Re: Pt (s)

Posted: Wed Feb 27, 2019 7:12 pm
by Nina Do 4L
Hi,

You would add Pt(s) or C(graphite) if there is no solid acting as an anode or cathode. You still would need to add a solid (either platinum or carbon graphite) in the presence of an aqueous solution because that represents the aqueous solution that the anode/cathodes would be in. So in the absence of a solid, add Pt(s) or C(gr)

Re: Pt (s)  [ENDORSED]

Posted: Wed Feb 27, 2019 7:32 pm
by Chem_Mod
The above answers are correct! Great job, everyone.

As for the homework problem, many students get confused by the solid I2. You need to remember that not all solids are conductors. You must have a metal for it to conduct, and I2 is not a conducting metal. Therefore, you need to add Pt as an electrode.