GAS LAW (Boyles, Charles and Gay Lussac).pptx

Gas Laws

1. GAS Laws

2. BOYLE’S LAW

3. Boyle’s Law: Pressure-Volume Relationship

4. volume- pressure relationship By Robert Boyle

5. States that the volume of a given mass of gas held at a constant temperature is inversely proportional to its pressure.

6. Focus on the yellow box molecules. What do you notice?

7. As the pressure goes up  the volume goes down 

8. p 1 v 1 = p 2 v 2 helps calculate the decrease or increase of the pressure of the people in the box

9. p 1 v 1 = p 2 v 2 Where: P 1 - initial pressure of the gas P 2 - final pressure of the gas V 1 - initial volume of the gas V 2 - final volume of the gas

10. Problem 1. Suppose you had gas in a 15.0 L container at 5.00 atmospheres pressure, and the volume is decreased to 0.500 L. What is the new pressure in the container?

11. Given: P 1 = 5.00 atm P 2 = ? V 1 = 15. 0 L V 2 = 0.500 L

12. Solution p 1 v 1 = p 2 v 2 P 2 = p 1 v 1 v 2

13. P 2 = P 2= 150 atm (5.00 atm )(15.0 L) 0.500 L

14. 2. If a scuba tank that has a capacity of 10.0 dm 3   is filled with air to 500.0 KPa , what will be the volume of the air at 702.6 KPa ? 

15.    [V 1 ][P 1 ]                   [P 2 ]                                                               V 2 =

16.   [10.0 dm 3 ][500.0kPa = [702.6 kPa ] V 2 =  7.11 dm 3 V 2

17. Solve for the following problem 1. The pressure exerted by a sample of gas in a 500 ml container is 1.35 atm. What pressure will the same amount of gas exert when the volume is decreased to 196 ml while the temperature is kept constant?

18. 2. Calculate the volume occupied by a gas at 900 torr and 25 C if it initially occupies a volume of 300 ml that exerts a pressure of 600 torr at that temperature.

19. 3. A sample of gas at 1.0 atm and 150 C occupies a volume of 1.25 L. What pressure is necessary to bring the volume down to 0.5 L at constant temperature?

20. Charle’s Law

21. Jacques-Alexandre-César Charles French physicist, studied the effect of temperature on the volume of a gas at constant pressure.

22. States that at constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature. Charles’ Law --Jacques Charles

23. Charles’ Law Illustration of Charles’ law The volume of the gas is affected by the change in temperature P= k V T

24. A mathematical expression of Charles’ Law is V 1 T 2 = V 2 T 1 = k V T V T or V= kT V 1   V 2 T 1    T 2 = or when P = k  or

25. Where: V 1 - initial volume of the gas V 2 - final volume of the gas T 1 - initial temperature of the gas T 2 - final temperature of the gas V 1   V 2 T 1    T 2 =

26. Sample Problems: 1. A 300 ml sample of gas at 125 C is heated to 155 C. What is its final volume when the pressure is kept constant? 2. An inflated balloon has a volume of 185 ml at a temperature of 52 C. What temperature must be reached in order to reduce its volume to half? Assume that the pressure remains constant

27. Gay-Lussac’s Law Temperature-Pressure relationship

28. Joseph Louis Gay-Lussac The person who is credited with the determination of the temperature-pressure relationship in gases at constant volume is.

29. Joseph Louis Gay-Lussac He deduced that the pressure of the gas is directly proportional to its temperature.

30. Gay-Lussac’s Law This means that when the temperature of gases increases its pressure also increases or vice versa.

31. Gay-Lussac’s Law State that At constant volume, the pressure of a fixed mass of gas is directly proportional to the absolute temperature.

32. Gay-Lussac’s Law can be expressed mathematically as P∝ t at constant volume It is can be written as: P= Kt or k= P/T

33. Gay-Lussac’s Law Since there is a direct proportionality between the pressure and temperature of gases at constant volume, it can be shown in this equation:  

34. SAMPLE PROBLEM The pressure of a nitrogen gas inside a rigid tank is 1.5 atmosphere at 30°C. What will be the resulting pressure if the tank is cooled to 0°C?

35. Given: Initial Conditions Final Conditions P1 = 1.50 atm P2 = ? T1 = 30°C + 273= 303K T2 = 0°C+273 = 273K   P 2 =   Formula:

36. Given: Initial Conditions Final Conditions P1 = 1.50 atm P2 = ? T1 = 30°C + 273= 303K T2 = 0°C+273 = 273K   P 2 =   Formula: P 2 =   P 2 =   P 2 = 1.35 atm Solution

37. 1. The helium tank has a pressure of 650 torr at 25°C. What will be the pressure if the temperature is tripled? Initial Conditions Final Conditions P1 = 650 torr P2 = ? T1 = 25°C + 273= 298K T2 = 75°C+273 = 348K   P 2 =   Formula: P 2 =   P2=   P 2 = 759 torr Solution

38. 2. At 20°C a confined ammonia gas has a pressure of 2.50 atm. At what temperature would its pressure be equal to 760. mmHg? Initial Conditions Final Conditions P1 = 250 atm P2 = 760mmHg T1 = 20°C + 273= 293K T2 = ?   1atm Formula: Convert the Pressure to atm:   T 2 =  

39. 2. At 20°C a confined ammonia gas has a pressure of 2.50 atm. At what temperature would its pressure be equal to 760. mmHg? Initial Conditions Final Conditions P1 = 2.50 atm P2 = 760mmHg= 1 atm T1 = 20°C + 273= 293K T2 = ?   T 2 =   Formula: T 2 =   T 2 =   T 2 = 117 K

40. A quantity of gas in a rigid container exerts a pressure of 780 torr at 35 C. What pressure will the same quantity of gas exert if the temperature is increased by 15 C?

41. A quantity of gas in a rigid container exerts a pressure of 780 torr at 35 C. What pressure will the same quantity of gas exert if the temperature is increased by 15 C? Initial Conditions Final Conditions P1 = 780 torr P2 = T1 = 35°C + 273= 308K T2 = 50°C +273= 323   Formula: P 2 =   P 2 =   P2=   P 2 =818 torr Solution