# Ideal gas Constant 8.314 or .08?

#### IdahoDoc

10+ Year Member
7+ Year Member
So I am sure the difference is between the units that you are given. I have always used 8.314 but while watching chad's videos he uses .08 or rather .1

Could someone explain to me when you can use the .1 and when you use 8.314?

#### IdahoDoc

10+ Year Member
7+ Year Member
For anything involving gases, use 0.08206 L atm/mol K.

For anything involving energy calculations, use 8.314 J/mol K.

Notice the units. For gases notice units of volume and pressure in the constant. For energy notice the Joules.

Hope this helps.
Could you give me an example when you would be using the ideal gas law for energy calculations?

#### 299678

I guess u need lots of more practices since there are lots of more cases for using 0.0821

#### CaptainSSO

7+ Year Member
Could you give me an example when you would be using the ideal gas law for energy calculations?
Like if you were calculating the kinetic energy of a mole of gas, KE = (3/2)RT.

You need the units to match up -- so in this case you use R = 8.314 J/K/mol. Multiplying that by T, in units of K, will cancel the K and leave you with Joules per mol.

#### UCB05

1atm = 101kPa

0.0821 = 8.315/101

0.0821 is for pressure in atms
8.315 is for pressure in kPa