1. 13.6 NOTES Temperature and Pressure Behavior

2. Temperature-Pressure Behavior of Gases
As temperature increases, the pressure of a gas increases when the volume is constant
Known as Gay-Lussac’s Law
P1/T1 = P2/T2 or P1T2 = P2T1
YOU MUST DO THE CALCUATION USING THE KELVIN TEMPERATURE

3. Example: A gas has a pressure of. 37 atm at 50 °C
Example: A gas has a pressure of .37 atm at 50 °C. What is the temperature at standard pressure?

4. The Combined Gas Law
Takes all three gas laws and combines them
Temperature, pressure, volume all change
P1V1T2 = P2V2T1

5. Example: If I initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 K, and then I raise the pressure to 14 atm and increase the temperature to 300K, what is the new volume of the gas?

6. Nonideal Gas Behavior
Gases are typically assumed to be ideal and behave according to kinetic molecular theory
Gases have what is called nonideal behavior at high pressure or low temperature
Low temperature
Particles move very slowly, which allows intermolecular forces to increase, which causes condensation
High pressure
Forces the particles to be close together, which allows the intermolecular forces to cause condensation

7. Ideal Gasses and Molar Volume
Avogadro’s Law
Equal volumes of gas at the same temperature and pressure have the same number of molecules
ALL gases have equal molar volumes if measure at same temperature and pressure
Molar Volume
Volume occupied by 1 mole of a substance
Molar volume at 0°C and 1 atm is 22.4 L.
Can use volume quantities like mole quantities in balancing equations and solving stoichiometry problems.

8. 2H2 + O2  2 H2O
- Coefficients can be moles or volume
- 2 moles H2, 2 L of H2