1. Homework #1: Vapor Pressure

2. Chapter 3: Gases Aim # 1 : How can you describe pressure?

3. There are four liquids in table H, which one do you recognize and use in your daily life?
Water

5. Do you know the common name for propanone, ethanol, and ethanoic acid?
Propanone: acetone
Ethanoic acid: vinegar
Ethanol: alcohol (there are different types of alcohols)

6. Use table k and identify the formula for ethanoic acid
CH3COOH
HC2H3O2

7. Use the reference table P and find the meaning of the prefix eth and prop
Eth: 2 carbons
Prop: 3 carbons

8. Use your reference table H and find the boiling point of propanone, ethanol, water and ethanoic acid at KPa
Propanone:56
Ethanol: 78
Water: 100
Ethanoic acid: 117

9. Why does ethanoic acid have a very high boiling point?
The intermolecular forces are very strong.

10. Where do we use propanone or acetone in our daily life?
Manicure…

11. Propanone is liquid at room temperature, the boiling point at STP is 56oC, this compound goes from liquid to gas very fast. Why? Weak intermolecular forces introduce the word volatile

12. 1. What happens when you open a coke can. 2. What do you hear. 3
1. What happens when you open a coke can? 2. What do you hear? 3. Do you have a theory for what is going on?

13. Why is it difficult to boil an egg on Mt. Everest?

14. Where do you observe more pressure?
Why?

15. Why does woman wearing snow shoes stay on top of the snow and the two girls sink in the snow?

18. What is pressure?
Pressure is defined as a measure of the force applied over a unit area. 

19. 1. Pressure
Pressure is defined as a measure of the force applied over a unit area. 
Pressure = Force
Area

20. What are the units of pressure?

21. How do we measure pressure?
Barometer:
atmospheric pressure
2. Manometer:
gas pressure
measures the difference between two different points of pressure.

22. What is STP in chemistry?

23. 2. Units of Pressure: Table A

24. What is the relationship between atmospheric pressure and weather conditions?

25. Atmospheric Pressure
Changing weather conditions

26. When the air sinks, more force pushes down toward the ground, so the barometric pressure increases. Conversely, when a low-pressure area moves in, the air rises, cools and condenses out moisture, which forms clouds and precipitation. Since a rising column of air above weighs less, the barometric pressure falls.

27. How does altitude affect pressure?
At sea level, the weight of the air presses on us with a pressure of approximately 14.7 lbs/in2. At higher altitudes, less air means less weight and less pressure. Pressure and density of air decreases with increasing elevation. 

28. Atmospheric Pressure
Changing Altitude

29. Sea Level STP: 101.3 Kpa or 1 atm
Table A

30. Mount Everest STP: 71 KPa

32. A. Barometer: device to measure air pressure
3. Measuring Pressure
Empty space
(a vacuum) Hg
Weight of the
mercury in
the column
atmosphere
(atmospheric
pressure)
A. Barometer: device to measure air pressure

33. Pressure
The mercury in the inverted tube is pushed upward by the force of atmospheric pressure pushing down on the surface of the mercury in the dish. The height of the mercury in the tube changes with changing atmospheric pressure. Under conditions of standard atmospheric pressure, the height of the mercury in the tube is 760 mm.

34. B. Manometer

35. 4. Units of Pressure 1 atmosphere or 1 atm 101.3 kilopascal or Kpa
760 millimeters of mercury or mm Hg
760 torr

36. 5. Boiling vs. Evaporation

37. A. Boiling Normal boiling point of H2O : 100 ºC
atmospheric pressure = vapor pressure
ATMOSPHERIC
PRESSURE
Normal boiling point of H2O : 100 ºC
VAPOR
PRESSURE

38. A liquid boils at a temperature at which its vapor pressure is equal to the pressure of the gas above it.

40. What is the difference between boiling point and evaporation?

41. B. Evaporation Molecules go from liquid to gas phase gas
H2O evaporates at different temperature.
liquid

42. Test your Understanding

43. 1. Convert 1 atm to KPa 101.3 Kpa 101.3 KPa 1 atm 101.3 KPa 1 atm
1 atm x
101.3 KPa
1 atm =
101.3 KPa
100 KPa

44. 2. . Convert 0.927 atm to KPa 0.927 atm X 101.3 Kpa = 1 atm

45. 3. The air pressure for a certain tire is 109 kPa
3. The air pressure for a certain tire is 109 kPa. What is this pressure in atmospheres?
1 atm
101.3 Kpa
109 Kpa X
= atm

46. Pressure Practice Convert the following: 145 mm Hg into kpa
900 mm Hg into torrs
4580 Pa into kPa
450 psi into kPa
5. 25 psi into atm
atm into KPa
109 kPa into atm
76.9 mm Hg into atm
98.6 torr into kPa
3 atm into kPa

47. End of the show