## Why don't you have to convert pressure into concentration when doing lnQ?

$E_{cell} = E_{cell}^{\circ}-\frac{RT}{nF}\ln Q$

Skyllar Kuppinger 1F
Posts: 52
Joined: Thu Jul 25, 2019 12:16 am

### Why don't you have to convert pressure into concentration when doing lnQ?

How can you have a Q value that contains both pressure and concentration?. I've been converting the pressures to concentrations this whole time Bc I thought you had to make it uniform , and didn't know why I was getting it wrong until someone sent me their solutions manual.
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Kaylee Sepulveda 4G
Posts: 100
Joined: Thu Jul 11, 2019 12:16 am

### Re: Why don't you have to convert pressure into concentration when doing lnQ?

Unless it specifically asks for Qp or Qc, I don't think you need to convert anything. And typically you're going to be given partial pressures for gases and concentrations for aqueous solutions, which I believe was the case in the problem you provided as an example.

Anish Natarajan 4G
Posts: 51
Joined: Thu Jul 25, 2019 12:16 am

### Re: Why don't you have to convert pressure into concentration when doing lnQ?

I believe it was mentioned in our discussion section that the ratios are going to be the same (although I could be wrong on this)

Skyllar Kuppinger 1F
Posts: 52
Joined: Thu Jul 25, 2019 12:16 am

### Re: Why don't you have to convert pressure into concentration when doing lnQ?

Kaylee Sepulveda 4G wrote:Unless it specifically asks for Qp or Qc, I don't think you need to convert anything. And typically you're going to be given partial pressures for gases and concentrations for aqueous solutions, which I believe was the case in the problem you provided as an example.

Right but you can convert partial pressure into concentration by using pv=nRT. But I guess you don't have to

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