2008 Final #3C: how voltage changes

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Anusha Sadda Lec4 Dis4F
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2008 Final #3C: how voltage changes

Postby Anusha Sadda Lec4 Dis4F » Sat Mar 14, 2015 10:47 am

In 3C of the 2008 final, can you explain why increasing the amount of a solid (PbS) would change the cell voltage? Thank you!

Niharika Reddy 1D
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Re: 2008 Final #3C: how voltage changes

Postby Niharika Reddy 1D » Sat Mar 14, 2015 12:02 pm

Adding a solid would change the cell voltage if the concentrations of ions are changed. Can you post the whole question?

Anusha Sadda Lec4 Dis4F
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Re: 2008 Final #3C: how voltage changes

Postby Anusha Sadda Lec4 Dis4F » Sat Mar 14, 2015 1:08 pm

I attached the question in a separate document.
Attachments
IMG_6818.jpg
2008 Final #3C

Chem_Mod
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Re: 2008 Final #3C: how voltage changes

Postby Chem_Mod » Sat Mar 14, 2015 1:34 pm

The sulfide ion from Na2S combines with Pb2+ to create the PbS. So when the solid forms, [Pb2+] goes down. Since lead is the anode, Pb2+ is a product. So Q goes down and E goes up.

Anusha Sadda Lec4 Dis4F
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Re: 2008 Final #3C: how voltage changes

Postby Anusha Sadda Lec4 Dis4F » Sat Mar 14, 2015 2:29 pm

That makes sense. Thank you!


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