COMBINED GAS LAW AND
AVOGADRO’S PRINCIPLE
COMBINED GAS LAW
P1V1
T1
=
P2V2
T2
EXAMPLE 1
A gas at 110 kPa and 30.0˚C fills a flexible container with an initial volume of
2.00L. If the temperature is raised to 80.0˚C and the pressure increased to 440
kPa, what is the new volume?
Given:
P1 = 110 kPa
P2 = 440 kPa
T1 = 30.0˚C =303K T2 = 80.0˚C = 353K
V1 = 2.00L
V2 = ?
110 (2.00)
303
=
440 (V2)
353
V2 = 0.583L ≈ 0.58L
EXAMPLE 2
An unopened bottle of soda contains 46.0 mL of gas confined at a pressure of
1.30 atm and temperature of 5.00˚C. If the bottle is dropped into a lake and sinks
to a depth at which the pressure and temperature changes to 1.52 atm and
2.90˚C, what will be the volume of gas in the bottle?
Given:
V1 = 46.0 mL
V2 = ?
P1 = 1.30 atm
P2 = 1.52 atm
T1 = 5.00˚C = 278K T2 = 2.90˚C = 275.9K
1.30 (46.0)
278
=
V2 = 39.0mL
1.52 (V2)
275.9
AVOGADRO’S PRINCIPLE
• States that equal volumes of gases at the same temperature and pressure
contain equal number of particles.
• The molar volume for a gas is the volume that one mole occupies at 0˚C and 1
atm or STP. This is equal to 22.4L
STP (Standard Temperature and Pressure) =
1atm and 0˚C or 1atm and 273K
1 mol of gas at STP = 22.4L
EXAMPLE 1
Calculate the volume that 0.881 mol of gas at standard temperature
and pressure (STP) will occupy.
0.881 mol
22.4 L
1 mol
= 19.7 L
EXAMPLE 2
How many moles of oxygen gas will be contained in a 5.00L flask at STP?
5.00L O2
1 mol O2
22.4 L O2
= 0.223 mol O2
EXAMPLE 3
Calculate the volume that 200.0 g of methane gas will occupy at STP.
200.0 g CH4
1 mol CH4
16.05 g CH4
22.4 L CH4
= 279.1 L CH4
1 mol CH4
EXAMPLE 4
How many grams of carbon dioxide gas are in a 0.75 L balloon at
STP?
0.75 L CO2
1 mol CO2
22.4 L CO2
44.01 g CO2
= 1.5 g CO2
1 mol CO2