1. Gas Laws

2. Gases Pressure Measuring Pressure Pressure is a measure of force/area
Kinetic Molecular Theory
•Gases contain particles-- these particles are in constant, random straight line motion.
•The particles collide with each other and the walls of the container.
when the particles collide they transfer energy but the total energy
remains constant (what is lost by one particle is gained by another).
• since the molecules are far apart -- the volume of the individual particle
is negligible compared to the total volume of the gas.
•Gas particles are not attract to each other
Pressure
Pressure is a measure of
force/area
Measuring Pressure
Barometer
units
mmHg
Torr
Atmosphere
kilo Pascal
lb/inch2
vacuum
As P inc. the Hg
Goes up the tube
Measure how high the Hg
Rises (mmHg or torr)
P = F/A
Air pressure Hg

4. Standard Temperature and Pressure
Average Kinetic Energy is directly proportional to the Kelvin Temperature
At absolute zero which is 0 degrees Kelvin or -273°C
There is no molecular motion
Convert °C to K
K = °C + 273
Standard Temperature and Pressure
STP Table A
Standard Temp = 0°C or 273 K
Standard Pressure = 1atm = 760 mm Hg = 760 torr = kPa

5. The Gas Laws Boyle’s Law Gay-Lussac’s Law Charles’ Law Avogadro's
Combined Gas Law
Avogadro's
Principle

6. Boyle’s Law PV =k Inc P dec. V P1V1 =P2V2 P V
At constant temperature, the volume of a given
mass of gas is inversely proportional to the
pressure.
PV =k
Inc P dec. V
P1V1 =P2V2 P V

8. Charles’ Law Inc. V, Inc. T V = k T V1 V2 = T1 T2 V T
at constant pressure, the volume of a given mass of gas is directly proportional to absolute temperature (Kelvin).
Inc. V, Inc. T
V = k T V1 T1 T2 V2 = V T

9. Gay-Lussac’s Law P = k Inc. P, Inc. T T P T P1 = P2 T1 T2
At constant volume,the pressure of a given mass of gas, is directly proportional to absolute temperature (Kelvin).
P = k T
Inc. P, Inc. T P T
P1 = P2
T1 T2

10. P1V1 = P2V2 T1 T2 Avogadro's Principle
Combined Gas Law--Boyle’s and Charles’ laws
used together. Reference Table T!
P1V1 = P2V2
T T2
If something is held constant,
Cross it out
Avogadro's Principle
equal volume of gases, under the same conditions of temperature and pressure, contain equal number of particles.
DIFFERENT MASSES!!

11. No attraction between particles Follows gas laws @ all temps.
Real Gases & Ideal Gases
No volume
No attraction between particles
Follows gas all temps.
& pressures.
Do have volume
Are Attractions between particles
Can condense or solidify
*Real gases differ most from ideal gas at low temps. and high pressures.

12. Real Gases
An ideal gas assumes that the molecules have no volume and no attraction to each other. However, real gas molecule do have some volume and are attracted to each other.
Real gas behaves ideally
Real gases deviate from ideal
High Temp (molecules move fast)
Low Pressure (molecules are far apart)
Low Temp (molecules move slow)
High Pressure (molecules are close together)
**H and He are most ideal b/c they
are small and can move fast.
PLIGHT= P-pressure
L-Low
I- ideal
G- gas
H- High
T- temperature