### Gas Constant

Posted:

**Sun Jan 26, 2020 6:43 pm**Which gas constant are we expected to use for the equation PV=nRT?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=51&t=57387

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Posted: **Sun Jan 26, 2020 6:43 pm**

Which gas constant are we expected to use for the equation PV=nRT?

Posted: **Sun Jan 26, 2020 6:46 pm**

0.08206 L.atm.mol.K

Posted: **Sun Jan 26, 2020 6:49 pm**

The gas constant depends on which measurement that the question uses (J, atm, bar, or torr usually) and it will be on the equations sheet.

Posted: **Sun Jan 26, 2020 9:57 pm**

The value for the gas constant depends on the units used in the specific question.

Posted: **Sun Jan 26, 2020 9:59 pm**

Use the gas constant that has the same units as the other values you are using in the calculation. For example, if your pressure is in atm, then use the gas constant that has the unit with atm (so they match and cancel).

Posted: **Sun Jan 26, 2020 10:05 pm**

Every question can possibly be different, so you can necessarily pinpoint down one equation. It just depends on the question and units.

Posted: **Sun Jan 26, 2020 10:07 pm**

There's a few different gas constants for different units but they are the same constant, just with different units. They are all on the formula sheet.

Posted: **Sun Jan 26, 2020 10:07 pm**

The gas constant (R) depends on what other units are given to you when calculating PV = nRT. The units are included on the formula/equation sheet.

Posted: **Sun Jan 26, 2020 10:27 pm**

Use the constant that includes the unit that is the same as the P in PV=nRT (so units cancel out nicely).

Posted: **Sun Jan 26, 2020 10:34 pm**

The gas constant needed will be based on the units of pressure. The constants should be on the formula sheets during tests.

Posted: **Sun Jan 26, 2020 10:57 pm**

The Gas Constant value is determined based on the pressure usually and other components in the ideal gas law equation. Pressure can be measured in atm, bar, etc, and R is represented in many of those units.

Posted: **Sun Jan 26, 2020 11:33 pm**

The constants will be given on the formula sheet during the exams.

Posted: **Sun Jan 26, 2020 11:41 pm**

It honestly depends what units P, V, and T are given. Typically we use .08206 L atm/mol K, but it really depends on units for the given values.

Posted: **Tue Jan 28, 2020 4:04 pm**

The gas constant is given on the formula sheet, make sure you chose the one with the units that apply to the equation.