Pt (s)  [ENDORSED]

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Mona El Masri 1F
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Joined: Fri Sep 28, 2018 12:20 am

Pt (s)

Postby Mona El Masri 1F » Wed Feb 27, 2019 1:26 pm

Do we add Pt solid to reactions that contain a liquid as well, or only aqueous and gas?

Ashley Zhu 1A
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Re: Pt (s)

Postby Ashley Zhu 1A » Wed Feb 27, 2019 2:41 pm

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

Sophia Ding 1B
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Re: Pt (s)

Postby Sophia Ding 1B » Wed Feb 27, 2019 3:11 pm

Why do you not need to add Pt(s) to liquids?

Celine Hoh 2L
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Re: Pt (s)

Postby Celine Hoh 2L » Wed Feb 27, 2019 3:16 pm

I think we also add Pt when both species of the same kind are in the same solution, say Fe2+ and Fe3+

Arta Kasaeian 2C
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Re: Pt (s)

Postby Arta Kasaeian 2C » Wed Feb 27, 2019 4:38 pm

We add Pt(s) to any side of the diagram (anode or cathode) that doesn't include a solid conductor within the reaction.

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Re: Pt (s)

Postby Daisylookinland » Wed Feb 27, 2019 5:53 pm

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?

Kyleigh Follis 2H
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Re: Pt (s)

Postby Kyleigh Follis 2H » Wed Feb 27, 2019 6:13 pm

Pt is included because in the cathode are two ion compounds in solution, so an inert electrode is needed.

Nina Do 4L
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Re: Pt (s)

Postby Nina Do 4L » Wed Feb 27, 2019 7:12 pm


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)

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Re: Pt (s)  [ENDORSED]

Postby Chem_Mod » Wed Feb 27, 2019 7:32 pm

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.

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