2. PHYSICAL CHARACTERISTICS OF GASES Or GAS LAWS

3. KINETIC MOLECULAR THEORY 1. Ideal gases vs. Real gases 2. Perfect elasticity 3. Average kinetic energy KE= ½ mv 2

4. Properties of gases 1. Expansion 2. Fluidity 3. Low density 4. Compressibility 5. Diffusion 6. Effusion

5. Pressure What is it??? Barometer/Manometer Millimeters/Torrs Atmospheres kiloPascals 1 atm. = 101.3 kPa = 760 mm 7.5 mm = 1 kPa

6. Conversions Change 800 mm to atm. and to kPa. Change 108 kPa’s to mm and atm.

7. Practice: Convert 699 mm to kPa and atm. Convert 1.05 atm to kPa and mm. Convert 101.9 kPa to mm and atm

8. Gases and Temperature Kelvin scale 0 o Celsius = 273K Conversion: Add 273 to Celsius temperature Change 25 o C to Kelvin Change 287K to Celsius Convert 45 o C to Kelvin Convert 30 K to Celsius

9. Boyle’s Law Robert Boyle theorized that the pressure and volume of a gas were indirectly proportional. What does this mean?? PV = k

10. Problems A gas is collected at a constant temperature of 25 o with a pressure of 689 mm and volume of 32 mL. Find the pressure if the volume goes to 55 mL? V 1 P 1 = V 2 P 2

11. One more: 45 mL of a gas is collected at 102.7 kPa. Find the volume if the pressure goes to 705 mm.

12. Charles’ Law Charles worked with temperature and volume of gases. Temperature and volume are directly proportional. V/T = k

13. Problems: V 1 / T 1 = V 2 / T 2 If 28 mL of H 2 are collected at 28 o C. What is the volume at 36 o C at constant pressure? Kelvin!!! If 35 mL of N 2 are collected at 31 o C,what is the temperature in o C if the volume rises to 45mL?

14. Gay –Lussac’s Law Gay- Lussac worked with pressure and temperature of gases. He said that pressure and temperature were directly proportional. P/T =k

15. Problems: A gas is collected at 43 o C and a pressure of 1.2 atm. Find the new pressure if the temperature drops to 21 o C. Kelvin!!! P 1 /T 1 =P 2 /T 2

16. Another problem: At constant volume,CO 2 is collected at 768mm with a temperature of 23 o C. Find the new temperature in o C of 99.1 kPa’s of pressure.

17. COMBINED GAS LAW PUT THE THREE EQUATINS TOGETHER AND MAKE INTO ONE. WRITE THIS EQUATION. V 1 P 1 / T 1 = V 2 P 2 / T 2

18. PROBLEMS 25 CM 3 OF HYDROGEN IS COLLECTED AT 26 0 C WITH A PRESSURE OF 1.2 ATM. FIND THE NEW VOLUME IF THE PRESSURE DROPS TO.98 ATM AND THE TEMPERATURE DROPS TO 22 0 C.

19. ANOTHER PROBLEM 78 cm 3 OF OXYGEN IS COLLECTED AT 42 O C WITH A PRESSURE OF 767mm. FIND THE NEW VOLUME AT STP.

20. Combined: 35 cm 3 of N 2 is collected at.98 atm of pressure with a temperature of 21 0 C. What is the new temperature in 0 C if the volume rises to 45 cm 3 and pressure rises to 788 mm?

21. Over water problems 15 liters of Chlorine is collected over water at 718 mm of pressure at a temperature of 60 o C. Find the new volume at 766 mm. This is Dalton’s Law of partial pressure. The total pressure of a container with many gases is the sum of the partial pressures.

22. ANOTHER PROBLEM: 25 mL of Fluorine gas is collected over water at 25 o C with a pressure of 102 kPa’s. Find the new pressure of 32 mL.

23. REVIEW 33 mL of O 2 is collected over water at 40 o C at a pressure of 697 mm. Find the new volume at 30 0 C with a new pressure of 1.01 atm.

24. Another one: 65 mL of F 2 are collected over water at 28 0 C with a pressure of 101.8 kPa. Find the new temperature of the gas at standard pressure.

25. For the quiz: 50.0 mL of a gas is collected over water at STP. Find the new volume if the new pressure is.97 atm and new temperature is 18 0 C.

26. Ideal gas law This is the last gas law and it involves all variables PLUS the mass of the gas. Variables: P= atmospheres R=.0821 L. Atm / K. mole V=liters n= moles T = Kelvin

27. THE FORMULA PV = n RT YOU MUST HAVE THE RIGHT UNITS TO USE THE CONSTANT!!

28. EXAMPLES What is the volume of H 2 gas if 15 grams is collected at 25 o C with a pressure of.89 atm.?

29. PROBLEM #2 What is the pressure of 3.5 grams of CO 2 that is collected at 24 o C with a volume of 550 mL?

30. PROBLEM #3 What is the mass of chlorine gas,Cl 2, if 4.8 liters are collected over water at 102.7 kPa’s with a temperature of 28 o C?

31. Problem #4 Find the volume of O 2 that is collected over water at 25 o C with a pressure of 736 mm and mass of 16 grams.

32. Molar mass problems What is the molar mass of 5.7 grams of a gas at 23 0 C with a volume of 4.1 liters at 1.1 atm of pressure? Formula: M = mRT/PV M = molar mass m= mass

33. A problem: What is the molar mass of 4 grams of a gas with a pressure of 791 mm at 42 o C with a volume of 450 mL?

34. Molar mass: What is the molar mass of a sample of Ar with.0045 moles that has a pressure of 725 mm at 21 0 C and a volume of 55 mL.

35. Molar mass What is the molar mass of CO if 6.5 grams occupies 2.5 liters at 21 o C with a pressure of 737 mm?

36. MOLAR VOLUME PROBLEMS To calculate molar volume and molar mass, you need to know that: 1 mole of any gas occupies 22.4 liters of volume at STP.

37. PRACTICE: What is the molar volume of 35 grams of CO 2 at STP?

38. More molar volume What is the number of moles of H 2 at STP if you collect 350 mL?

39. Molar volume with a twist: How many grams of SO 2 gas at STP occupies 450 millilters of volume?

40. Graham’s Law The rate of the movement of a gas is dependent on its mass. Which gas will diffuse or effuse faster? N 2 or F 2 ??

41. Ideal gas law review What is the mass of 68 mL of Ne with a pressure of 99.7 kPa’s that is collect OVER WATER at 26 o C?

42. Molar volume review How many liters does 18 grams of Cl 2 occupy at STP?