### Conversion of R

Posted:

**Fri Mar 16, 2018 2:15 pm**When using the Pv=nRt formula, do you represent R as 8.314 or 8.206 x10^-2?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=129&t=29985

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Posted: **Fri Mar 16, 2018 2:15 pm**

When using the Pv=nRt formula, do you represent R as 8.314 or 8.206 x10^-2?

Posted: **Fri Mar 16, 2018 2:39 pm**

This would depends on the units you are trying to cancel. If pressure were in atm you would use .0826 so that the units would cancel

Posted: **Fri Mar 16, 2018 3:04 pm**

what if pressure was not given to you? Would you use 8.314?

Posted: **Fri Mar 16, 2018 3:48 pm**

It still depends on what you're solving for. If you're not given pressure and solving for pressure, then you would use 8.206 x 10-2 L·atm·K-1·mol-1, because that would cancel out so that you get atmospheres for the units of pressure. If you're not given pressure and trying to solve for work, then you use 8.314 J·K-1·mol-1 because that would cancel out so that you get Joules for your units of work.

Posted: **Fri Mar 16, 2018 5:21 pm**

You would have to see what units you are using or solving for. If you are trying to find joules, you will be using 8.314

Posted: **Fri Mar 16, 2018 6:21 pm**

I've found that I generally use 8.314J/mol.K because it cancels out n (mol) and T(K).

Posted: **Sun Mar 18, 2018 4:05 am**

Check the units behind the constant R to see what needs to cancel out in the problem you are solving.

Posted: **Sun Mar 18, 2018 5:22 pm**

youll use 8.314 most of the time but whenver the units are L.atm then you use 8.206