Gases:

Mass

Easily compressed

Completely fill their containers

Diffuse rapidly

Exert pressure (which depends on its temperature)

Have perfectly elastic collisions

Are NOT attracted to each other

Amount – (n) – Moles

Volume – (V) – L, mL

Temperature - (T) – Measured in Kelvin

K = °C + 273

Pressure - (P) - atm., Pa, kPa, mmHg

Standard Temperature = 0°C = 273K

Standard Pressure = 1 atmosphere

*Remember, we ALWAYS use Kelvin!!!

0 K or -273°C

When all motion ceases

Lowest temperature possible

Pressure exerted by the air in the atmosphere

1 atmosphere (atm) 101,300 Pa 101.3 kPa 760 mmHg

Convert:

1) 756 mm Hg = _________ atm

2) 4.5 atm = __________ kPa

3) 65.01 kPa = ________ atm

4) 567 K = _______°C

5) 456°C = ________ K

0.995

460 0.6418

294 729

The pressure and volume of a sample of gas at constant temperature are inversely proportional to each other.

As P,V

P1V1 = P2V2

P

P

T

T

Plunger/Bike Pump ◦ If you have ever tried to force air into a bike with a

plunger your volume decreases and the pressure increases (making it harder to pump)

2.00 L of a gas is at 740.0 mm Hg pressure. What is its volume at standard pressure?

1.95 L

2.00 L (740.0 mmHg) = x (760 mmHg)

At constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature.

As V, T

V1 V2

T1 T2

=

P

P

T

T

A Hot Air Balloon ◦ One heats up the air in the balloon and what

happens to the volume?

4.40 L of a gas is collected at 50.0°C. What will be its volume upon cooling to 25.0 °C?

4.06 L

4.40 / (323 K) = x / (298 K)

At constant volume the temperature and pressure of a sample of gas are directly proportional to each other.

As P, T

P1 P2

T1 T2 =

P P

Aerosol Can in a Fire ◦ What happens to the temperature and pressure

when an aerosol can is placed in a fire?

5.00 L of a gas is collected at 22.0 °C and 745.0 mm Hg. What would be the required temperature (in Celsius) to change the pressure to standard pressure?

27.9 °C

745.0/ (295 K) = 760 / (x)

Combines Boyle, Charles and

Gay-Lussac into one equation!

P1V1 P2V2

T1 T2

=

2.00 L of a gas is collected at 25.0 °C and 745.0 mm Hg. What would be the volume at STP?

1.8 L

(2.00) (745.0)/ (298 K) = 760 (x) / (273)

Equal volumes of gases at the same temperature and pressure contain an equal number of particles (atoms or molecules.

As V, n

V1 V2

n1 n2

=

P

P

T

T