1. Last Unit of Chemistry! (not the last lecture, but hey it’s something)

2. The Gas Laws
Boyle’s law - pressure of a fixed amount of gas at a constant temperature is inversely proportional to the volume of the gas. (volume goes up, pressure goes down) at constant temperature
P1V1 = P2V2

3. The Gas Laws
Charles’s Law - the volume of a gas maintained at constant pressure is directly proportional to the absolute temperature of the gas. (at constant pressure)

4. Gay Lussac’s Law – the pressure exerted by a gas is directly related to the temperature when moles and volume are held constant.

5. The Gas Laws
Avogadro’s law - the volume of a sample of gas is directly proportional to the number of moles in the sample at constant temperature and pressure.

6. The Gas Laws
The combined gas law can be used to solve problems where any or all of the variables changes.

7. PVnRT4LYFE!
The ideal gas equation (below) describes the relationship among the four variables P, V, n, and T.
PV = nRT
An ideal gas is a hypothetical sample of gas whose pressure-volume-temperature behavior is predicted accurately by the ideal gas equation.

8. The Ideal Gas Equation
The gas constant (R) is the proportionality constant and its value and units depend on the units in which P and V are expressed.
PV = nRT

9. The Ideal Gas Equation
Standard Temperature and Pressure (STP) are a special set of conditions where:
Pressure is 1 atm = kpa = 760 mmHg = 760 Torr
Temperature is 0°C ( K)
When converting from one unit of pressure to another, use the numbers above and factor label method.
kpa 760 mmHg 760 Torr
1 atm atm atm

10. Pressure units 5.34 atm to mmHg 97.3 kpa to Torr
5.34 atm x 760 mmHg = mmHg atm
97.3 kpa to Torr
97.3 kpa x atm x 760 Torr = kpa atm

11. Dalton’s law of partial pressure - the total pressure exerted by a gas mixture is the sum of the partial pressures exerted by each component of the mixture:

12. Dalton’s law
Not an equation like the rest of them, but more of a concept
Works because we are saying that all gasses, regardless of kind, behave the same and therefor all take up the same space.
Therefore, if a pressure is made of 10 moles of ten gasses, each one exerts 1/10th of the total pressure.
If 5.4 atm is made up of 2 moles of fluorine gas, and 3 moles of chlorine gas, how much pressure do each exert?

13. Gas Mixtures
Determine the partial pressures and the total pressure in a 2.50-L vessel containing the following mixture of gases at 15.8°C: mol He, mol H2, and mol Ne.
Solution:
Step 1: Since each gas behaves independently, calculate the partial pressure of each using the ideal gas equation:

14. Gas Mixtures
Determine the partial pressures and the total pressure in a 2.50-L vessel containing the following mixture of gases at 15.8°C: mol He, mol H2, and mol Ne.
Solution:
Step 2: Use the equation below to calculate total pressure.
Ptotal = atm atm atm = 2.17 atm