Ideal Gas Law
PV = nRT
This formula is used when you have a gas and you are trying to find moles, volume,
pressure, or temperature.
P = pressure
n = number of moles
V = volume
T = temperature in Kelvin
R = Universal Gas Constant
R = 0.0821 atm L
mol K
1.
R = 62.4 mmHg L
mol K
Calculate the volume, in liters, of 2.15 moles oxygen gas at 298 K and 1.25
atm.
Step 1 List the information
P=
1.25atm
n = 2.15moles
V=
?
R = 0.0821 atm L
mol K
T = 298K
Step 2 Write down the formula
PV= nRT
V= nRT
P
Step 3 Plug the numbers into the formula
(2.15moles)(298K)(0.0821atmL)
(1.25atm)(mole K)
Step 4 Report the answer
2.
3.
4.
42.08 L
What are the values for the temperature and pressure at STP?
Pressure=
1
atm or
760
mmHg
o
Temperature= 0
C or
273
Kelvin
What is the volume of 1 mole of a gas at 273 K and 1 atm?
V= nRT
V=
(1 mole)(0.0821 atm L)(273K) = 22.4L
P
1 atm (mole K)
If a 2.8 mole sample of gas initially occupies 54 L at 3.8 atm, what is its
temperature in K?
T= PV
nR
T=
(3.8 atm)(54 L) mole K
=
(2.8 mole)(0.0821 atm L)
892.6 K
5.
How many moles of gas are present if a particular sample occupies 2.94 L
with a pressure and temperature of 450 torr and 315 K respectively?
n = PV
RT
6.
=
0.0223 moles
T=
(1 atm)(224 L) mole K
(4 mole)(0.0821 atm L)
= 682 K 409 oC
(0.0010 torr)(0.001 L) mole K
(193 K)(62.4 torr L)
=
8.3 x 10-11 moles
V=
(1.2 mole)(0.0821 atm L)(200 K) = 39.4L
0.5 atm (mole K)
(800 torr)(0.200 L) mole K
(373 K)(62.4 torr L)
=
0.00687 moles
What is the pressure of gas if 5 moles occupies 2 liters at and 298 K?
P= nRT
V
12.
(1 atm)(0.5 L) mole K
(273 K)(0.0821 atm L)
How many moles would be present under the following conditions 200 mL of
gas at 800 torr are at 1000C?
n=
11.
n=
What is the volume of 1.2 moles of gas at 0.5 atm and 200 K?
V= nRT
P
10.
0.0673 moles
How many moles of an ideal gas are in 1.0 mL if the temperature is -80 °C
and the pressure is 0.0010 torr? (Remember to convert from oC to K)
n=
9.
=
What is the temperature in oC if you have 4 moles of gas that occupy 224 L
liters at 1 atm? (Remember to convert from K to oC)
T= PV
nR
8.
(450 torr)(2.94 L) mole K
(315 K)(62.4 torr L)
How many moles of gas are present in a 500 mL container at STP?
n = PV
RT
7.
n=
P=
(5 mole)(0.0821 atm L)(298 K) = 61.16 atm
2 L (mole K)
What is the pressure of gas if 14.8 moles occupies 3.75 liters at and 32 °C?
(Remember to convert from oC to K)
P= nRT
V
P=
(14.8 mole)(0.0821 atm L)(305 K) = 98.8 atm
3.75 L (mole K)