How do we know which gas constant to use?

[Emma Kelly 3L]

In the equation sheet, multiple values are listed for the ideal gas constant (with different units). I've always used .08206 L·atm·K-1·mol-1 as the gas constant in previous classes, but this example in lecture used 8.314 J·K-1·mol-1. Is this because we aren't given volume in liters or perhaps because we're solving for volume?

[Harsimer Bal 3K]

The ideal gas constant used depends on the units provided in the question and are using to solve the question. If the question uses L and atm, you will probably use 8.206*10^-2 L*atm/K*mol and if the question uses J, you'd use 8.314J/K*mol. In the example from lecture today, 8.314J/K*mol was used for R because the enthalpy was given in kJ. There was no mention of liters in the question so I would just stick to the units given in the problem to see which gas constant to use.

[Ashley Hiti 1K]

Similar to what Harsimer said you have to see which gas constant has the units that will allow it to cancel out others given in the problem.

[carterwink2K]

It is safe to assume that we will be using the J/K*mol constant for the ideal gas law. Otherwise you should check which units are present in order to use the right one.

[Shreya Arcot 3K]

To figure out what gas constant to use, you can check the units of the other values and use the gas constant with those units. This way, units can cancel out.

[Maggie Clark]

I believe for at least the midterm it should be given!

[Madeline Ellmore 2C]

I would assume the gas constant will be given, but if not, check the units of of the units given/calculated and match the gas constant to it.

[Preethika Praveen 2G]

The gas constant that you use should match the units used in the problem. Therefore, if the units are L and atm, you will use 8.206*10^-2 L*atm/K*mol and if the units are J, you will use 8.314J/K*mol

[Milan Vognarek 1A]

Just make sure that the units of the gas constant correspond to those given in the problem, so that they may cancel out.