1. Gas Laws
PSquires
2011

2. Properties of Gases
 Gases expand to fill the container.
 Gases take on the shape of the container.
 Gases are highly compressible.
(Can be liquefied at high pressure).
 Gases have low densities.
 Gases mix uniformly.

3. Kinetic Molecular Theory
1. Molecules are in constant random motion
2. A gas is mostly empty space
3. No intermolecular forces
4. Collisions are elastic. No change in energy.

4. Use Kelvin degrees!
K = C + 273
Temperature conversion

5. Pressure Measurements
Standard sea level pressure is…
1.00 atmospheres (atm)
760. mm Hg
760. torr (from Torricelli)
101.3 kilopascals (kPa)
14.7 lb/in 2

6. Boyle’s Law
Pressure
Volume
At constant temperature, pressure is inversely
proportional to volume.

7. Boyle’s Law
1/Pressure
Volume
At constant temperature, pressure is inversely
proportional to volume.

8. Boyle’s Law
At constant temperature, pressure is inversely
proportional to volume.
P1V1 = P2V2

9. Boyle’s Law Problem:
The pressure of some N2 gas is
4.53 atm when the volume is
30.0 mL. What is the pressure
when the volume is increased to
150. mL at a constant T?
P1V1 = P2V2

10. Charles’ Law
Volume
Temperature
At constant pressure, volume is
directly proportional to temp.

11. Charles’ Law
At constant pressure, volume is
directly proportional to
temperature.
V1 V2
T1 =T
2

12. Charles’ Law Problem:
A quantity of oxygen gas
has a volume of 50.0 mL
at 30.0 C. Find the
volume of O2 gas when
the temperature is
increased 150.0 C at a V1 V2
constant pressure. T = T2
1

13. Combined Gas Law
The combined gas law is the
combination of Boyle’s Law and
Charles’ Law.
P1V1 P2V2
=
T1 T2