Do Now (5 min)

1. Do Now (5 min) 1. What happens to the pressure of a gas when you raise the temperature? 2. What happens to the pressure of a gas when you INCREASE the volume?

2. Do Now Discussion What happens to the pressure of a gas when you raise the temperature? What happens to the pressure of a gas when you INCREASE the volume? Pressure INCREASES Pressure DECREASES

3. Do Now – 4/23/10 • What happens to pressure as volume increases? • What happens to volume as pressure increases? • What happens to Mr. Sandine as your grade decreases? Setup Cornell Notes – “Gas Laws”

4. The Gas Laws 4-18-10 Cornell Notes Worksheet Relay

5. Agenda • Do Now • Cornell Notes (3 gas laws) • Worksheet Relay

6. Remember… • Gases have four different properties we can measure in numbers: • According to Kinetic Molecular Theory, gases have these properties because they are made of moving particles.

7. Why are we learning about gases? • Gases affect our lives in many ways • We need it to survive (oxygen) • Air pressure is responsible for our ears and lungs to function • To predict these behaviors, we need to be able to use the three gas laws that gases obey.

8. Boyle’s Law P α 1/V • Pressure and volume are INVERSELY proportional if moles and temperature remain constant • When P goes up, V goes down and vice versa Robert Boyle (1627-1691). Son of Earl of Cork, Ireland. P1V1 = P2V2

9. Example 1: If the pressure of a gas starts at 2 atm and it’s volume is 5.0 L, what happens to the pressure when the volume increases to 15.0 L? P1V1 = P2V2 Before After (x atm) (15.0 L) (2 atm) (5.0 L) = (15.0 L) (15.0 L) If we change the volume, the pressure changes to 0.67 atm

10. Example 2: If the pressure of a gas starts at 5 atm and it’s volume is 10.0 L, what happens to the pressure when the volume decreases to 5.0 L? P1V1 = P2V2 Before After (x atm) (5.0 L) (5 atm) (10.0 L) = (5.0 L) (5.0 L) If we change the volume, the pressure changes to 10.0 atm

11. Boyle’s Law • A bicycle pump is a good example of Boyle’s law. • As the volume of the air trapped in the pump is reduced, its pressure goes up, and air is forced into the tire.

12. Charles’s Law V α T • Volume and temperature are DIRECTLY proportional IF moles and pressure remain constant • When V goes up, T goes up V1 = V2 T1T2 Jacques Charles (1746-1823). Isolated boron and studied gases. Balloonist.

13. Example 1: If the volume of a gas is 4.0 L and it’s temperature is 50 K, what happens to the volume if the temperature changes to 75 K? V1 = V2 T1T2 Before After 4.0 L X L = 50 K 75 K If we change the temperature, the volume changes to 6.0 L

14. Example 2: If the volume of a gas is 8.0 L and it’s temperature is 200K, what happens to the volume if the temperature changes to 100K? V1 = V2 T1T2 Before After 8.0 L X L = 200K 100K If we change the temperature, the volume changes to 4.0 L

15. Charles’s Balloon • Heat up the air (raise the tempreature), the volume increases (balloon inflates)

16. Gay-Lussac’s Law P α T • Pressure and temperature are DIRECTLY proportional IF moles and volume remain constant • When P goes up, T goes up Joseph Louis Gay-Lussac (1778-1850) P1 = P2 T1T2

17. Example 1 If the pressure of a gas is 5.0 atm and the temperature is 50 K, what will the temperature be if the pressure decreases to 3.0 atm? P1 = P2 T1T2 Before After 5.0 atm 3.0 atm = 50 K X K If we change the pressure, the temperature drops to 30 K

18. Example 2 If the pressure of a gas is 5.0 atm and the temperature is 50 K, what will the temperature be if the pressure increases to 10.0 atm? P1 = P2 T1T2 Before After 5.0 atm 10.0 atm = 50 K X K If we change the pressure, the temperature drops to 100K

19. Combined Gas Law • Good news! We don’t have to memorize all three laws! Since they’re all related, we can combine them into ONE equation! • If you only need one of the other gas laws, you can cover up the item that is constant and you will get that gas law! • = P1 V1 P2 Boyle’s Law Charles’ Law Gay-Lussac’s Law V2 T1 T2

20. Practice • Complete the worksheet problems on a SEPARATE sheet of paper • Have Mr. Sandinecheck your work after each round BEFORE you move on to the next round! • Next Monday, we will be in the computer lab (342) • Trifolds are due today • If you have any other HW (Study guides, vocab, 13.1, etc, make sure you get it checked in)