The Ideal Gas Law

```The Ideal Gas Law
PV=nRT
P = Pressure
V = Volume
 n = Number of Moles
R = ideal gas constant
T = temperature in Kelvin
QuickTime™ and a
Sorenson Video 3 decompressor
are needed to see this picture.
R -The ideal gas constant
Depends on unit of pressure
0.0821 L . Atm / K . mol
62.4 L . mmHg / K . mol
8.31 L . kPa / K . mol
Ideal Gas Law
example problem
 Calculate the pressure of 1.65 g of helium gas at
16.0oC and occupying a volume of 3.25 L?
 You will need g to moles and Celsius to Kelvin:
 1.65 g He 1 mole He

4.0 g He = 0.412 mol He
 K = oC + 273 ; 16. 0 + 273 = 289 K
 For this problem you will need to pick an R value. For
this problem I will choose to use the R value
containing kPa. I picked it. You can’t do anything
about it. So; just try and stop me.
 Plug and Chug baby, get ‘R done. Do it. Come on I
dare ya.
Ideal Gas Law
example problem
 P x 3.25 L = 0.412 mol x 8.31 kPa . L x 289 K

mol . K
 Do the algebra and solve; if you do it right, guess
what? You get the answer right. Neat concept, huh?
 = 304 kPa
 How many moles of gas are present in a sample of
Argon at 58oC with a volume of 275 mL and a
pressure of 0.987 atm.
Ideal Gas Law
example problem