1. (same ratio for every gas)
So far we’ve seen…
constant PV nT
V  1/P (Boyle’s law)
V  T (Charles’s law)
P  T (Gay-Lussac’s law)
V  n (Avogadro’s law)
= R
(same ratio for every gas)
R = L∙atm mol∙K
ideal gas constant:
PV = nRT
Ideal Gas Law
NO Units of : mL , mmHg , kPa , grams , °C

2. (Standard Temperature & Pressure)
STP
(Standard Temperature & Pressure)
K & 1 atm

3. Ideal Gas Law Calculations
A 5.00 L balloon is at atm and 25oC.
How many moles of gas are in the balloon?
PV = nRT
R =
(0.855 atm)(5.00 L) =
n ( )(298 K)
A balloon shrinks when submerged in cold water
(0.855)(5.00)
( )(298) = n
n =
0.175 mol

4. Ideal Gas Law Calculations
What is the pressure of mol He gas in a volume of 8.12 L at 0.oC?
PV = nRT
R =
P (8.12 L) =
(0.435mol )( )(273 K)
(0.435)( )(273)
(8.12) P =
P =
1.20 atm

5. Ideal Gas Law Calculations
A sample of aluminum chloride gas weighing g at 350.oC and 760. mmHg of pressure occupies a volume of 19.2 mL.
Calculate the Molar Mass of the gas.
PV = nRT
R =
(1.00 atm)( L) =
n ( )(623 K)
n =
mol
__ g_
mol
Molar Mass
grams
mole
M = =
AlCl3 =
133 g/mol