1. Gases: Combined Gas Law

2. Properties of Gases Have a Mass Are compressible Fill empty space completely Diffuse rapidly Exert pressure

3. Converting between units of pressure Pressure can be measured in a variety of ways. To convert: 1. Rewrite out the conversion factor as a denominator. 2. Match the units from the problem to the units in the conversion factor. 3. Cross multiply to convert.

4. Example What is 56 mmHg in kilopascals?

5. Example How many kilopascals are in 7.67 atm?

6. Example How many mmHg are in 56789 kilopascals?

7. You Try What is 34.6 mmHg in kilopascals? How many kilopascals are in 4.56 atm? How many mmHg are in 6.78 torr?

8. A New Measurement of Temperature Temperature can also be measured in a unit known as Kelvin. 0°C = 273 K Note! Kelvin is an absolute temperature. (No negative numbers)

9. Example 45°C is what in Kelvin?

10. Example 5 Kelvin is what in Celsius?

11. You Try 500 Kelvin is what in Celsius? 95°C is what in Kelvin? 4.5°C is what in Kelvin? 100 Kelvin is what in Celsius?

12. Pressure, and temperature, and volume. Oh my! The pressure, temperature, and volume of a gas are all linked. As temp goes up, volume and pressure goes up. (Direct) As pressure goes down, volume goes up (Indirect)

13. Gas Law A way to measure the relationship between pressure, volume, and temperature

14. Combined Gas Law P = V = T = 1 shows 2 shows

15. Units Temperature must be in Kelvin Pressure and volume can be in whichever unit you want, as long as you keep it in that unit (this means the unit of P 1, V 1 must be the same as the unit of P 2, V 2 )!

16. Example A gas at 6.00 atm and 20 mL is moved to a container with a volume of 10 mL. What is the new pressure?

17. Example A gas at 295 K and 3 atm is cooled to -45 C. What is the new pressure?

18. Example A gas at 295 K, 3 atm, and 230 L is cooled to 195 K and a volume of 15 mL. What is the new pressure?

19. You Try A gas at 25 K and 5.67 atm is cooled to 10 K. What is the new pressure in Torr? A gas at 29.5°C, 30 kPa, and 230 mL is cooled to 19 K and a volume of 15 mL. What is the new pressure?