Section 14.2 lecture (part B) for Honors & Prep Chemistry

2. The combined gas law Uses three gas variables to describe a gas sample at two different times. If a variable does not change (is constant) it can be removed from the equation. P 1 V 1 P 2 V 2 T 1 T 2 =

5. INDIRECTLY PROPORTIONAL aka INVERSELY PROPORTIONAL

6. Boyle Problem V 1 = 30.0L All math examples should be in your notes L measures Volume(V)

7. Boyle Problem V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa kPa measures Pressure(P)

8. Boyle Problem V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa These two values go together because they describe the gas at the same moment.

9. Boyle Problem V 1 = 30.0L V 2 = ? P 1 = 103 kPa This is the unknown

10. Boyle Problem V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa This is a pressure value

11. Boyle Problem V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa These two values go together because they describe the gas at the same moment.

12. Boyle Problem Temp is constant and I need an equation that relates pressure and volume. P 1 V 1 = P 2 V 2 V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa P 1 V 1 = P 2 V 2 T 1 T 2

13. Boyle Problem P 1 V 1 = P 2 V 2 103 kPa x 30L = 25.0 kPa x V 2 ___________ ___________ 25.0 kPa 25.0kPa = 124 L P  ,V  GOOD! V 1 = 30.0L V 2 = ? P 1 = 103 kPa P 2 = 25.0 kPa

14. for Sample Problem 14.1

17. DIRECTLY PROPORTIONAL

18. 14.2 T 1 = 24  C T 2 = 58  C V 1 = 4.00L V 2 = ? T must be in Kelvins!! + 273 = 297K + 273 = 331K V 2 = 4L  297K x 331K = 4.46 L T  V  GOOD! 4.00L V 2 297 K 331 K =

19. for Sample Problem 14.2

22. 14.3

26. for Sample Problem 14.3

32. for Sample Problem 14.4