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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
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