1. Gases

2. Gases and Pressure
Pressure is the measure of the amount of force (Newton) per unit area (cm2)
Pressure can be measured in several different units
Torr or mmHg
kPa
Atm
1atm = kPa = 760mmHg (or Torr)

3. Pressure Conversions

4. STp and Dalton’s Law Standard Temperature and Pressure
0ºC and 1 atm
Dalton’s Law of Partial Pressure
The sum of the pressures of all the gases in a system is equal to the total pressure of the system

5. Dalton’s Law of Partial Pressure

6. Boyle’s Law Boyle’s Law Robert Boyle
States that at a constant temperature, the volume of a gas varies inversely with pressure
V1 x P1 = V2 x P2

7. Boyle’s law

8. Charles’s Law Charles’s Law Jacques Charles
States that at a constant pressure and mass, the volume of a gas and the temperature are directly proportional
V1 / T1 = V2 / T2
Temperature must be in Kelvins

9. Charles’s Law

10. Gay-Lussac’s Law Gay-Lussac’s Law Joseph Gay-Lussac
States that at a constant volume, the pressure of a gas and the temperature are directly proportional
P1 / T1 = P2 / T2
Temperature must be in Kelvins

11. Gay-Lussac’s Law

12. Combined Gas Law The combined gas law combines all three gas laws
(V1 x P1) / T1 = (V2 x P2) / T2
Temperature must be in Kelvins

13. Gas Stoichiometry and Ideal Gas Law
Gay-Lussac’s Law of Combining Volumes
States that when temperature and pressure are held constant, volumes of combined gases can be expressed as simple whole number ratios
Avogadro’s Law
State that equal volumes of gases at the same temperature and pressure contain equal number of particles
These two laws establish a relationship between gas volumes and the number of moles

14. Gas Stoichiometry Relationship between volume and moles
1 mol = 22.4 L of STP = 6.02 x 1023 particles = molar mass (grams)

15. Gas Stoichiometry

16. Ideal Gas Law
Factors in not only pressure, temperature, and volume but also the number of particles (moles)
The amount of particles in a system can also affect the other variables as well
PV = nRT
P = pressure (kPa)
V = volume (L)
n = number of moles
R = Ideal gas constant (8.314 L x kPa/mol x K)
T = Temperature (Kelvins)

17. Ideal Gas Law