What does R stand for?

[Mike Matthews 1D]

The equation relating the heat capacity of an ideal gas at constant pressure and the heat capacity of an ideal gas at constant volume is:
Cpm=Cvm + R
That being said, what is R? Is it the gas constant? If so how does one go about deciding which value to use for R?

[Kailey Brodeur 1J]

R is the ideal gas constant. You decide what value of R you should used based upon what units you are using.

[Jessica Nunez 1I]

As mentioned, R is the gas constant which is equal to . . .
8.314 J.K^-1.mol^-1 = 8.206 x 10^-2 L.atm.K^-1.mol^-1 = 8.314 x 10^-2 L.bar.K^-1.mol^-1 = 62.364 L.Torr.K^-1.mol^-

[Nicole Jacobs 1C]

R should also be given on the formula and constant sheet Lavelle gives us for the test

[Sarah Rutzick 1L]

Going off of what everyone else said, there are several different gas constants so its important to use the one that ensures the correct units cancel out.

[Adrian Lim 1G]

Just to clarify, R is the ideal gas constant and its units are given per mole. Thus, when you are using this for q = mcdeltat, make sure the m is amount given in moles so the moles with the c would cancel.

[Alejandra Rios 1L]

R is a constant which is used in ideal gas calculations. There are several values which you can use for R depending on what unit of pressure you are working with. These values will be given!

[Juanyi Tan 2K]

The one that we most commonly use in thermochemistry is R = 8.314 J·K-1·mol-1

[Justin Folk 3I]

Heat constant. When do you use 8.314 and when do you use 0.00821?

[Cassandra Mullen 1E]

Heat constant. When do you use 8.314 and when do you use 0.00821?

Looking at the units helps you to determine which R to use. If you're using the ideal gas equation and pressure is in atm and volume is in L, then you would use 0.00821 Latm/molK. Homework problem 8.49 is an example of using the other R value, 8.314 J/Kmol.

[Justin Folk 3I]

Yes, you're right sorry. THere's multiple R. You need to look at the units, on the third row of equation sheet. THanks

[Jaewoo Jo 2L]

I think until now, we've mostly seen the R values with atm or joules, and like what everyone said above, you just use the value with the units that cancel with corresponding units in your calculations.

[Annie Lieu-1H]

The ideal gas constant! Like everyone said, make sure to look at the equations sheet and look at the right units to use for numbers in a particular problem.

[Warda Sahib 2J]

R is the ideal gas constant.