### R Constant

Posted:

**Sun Jan 19, 2020 11:24 am**How do we know which R constant to use in calculation?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=123&t=56611

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Posted: **Sun Jan 19, 2020 11:24 am**

How do we know which R constant to use in calculation?

Posted: **Sun Jan 19, 2020 11:53 am**

R is the universal gas constant, which is 0.082 L.atm/mol.K

Posted: **Sun Jan 19, 2020 12:16 pm**

Kimberly Koo 2I wrote:R is the universal gas constant, which is 0.082 L.atm/mol.K

there are different R constants for different units though

Posted: **Sun Jan 19, 2020 12:55 pm**

You should use the R constant that has units that cancel out with the other units in the equation. For example, in PV=nRT, we use 0.08206 (L*atm)/(mol*K) because it cancels with the pressure, volume, moles, and temperature.

Posted: **Sun Jan 19, 2020 1:21 pm**

Use the R constant that uses the appropriate unit of pressure.

Posted: **Sun Jan 19, 2020 1:55 pm**

R is the universal gas constant and has the units of the other variables (L, atm, etc...)

Posted: **Sun Jan 19, 2020 6:29 pm**

R is usually 0.082- it may also be on the formula sheet

Posted: **Sun Jan 19, 2020 9:31 pm**

The R values are different depending on the temperature used in the reaction