1. Ch Liquids & Solids
III. Changes of State
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2. A. Phase Changes
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3. A. Phase Changes Evaporation
molecules at the surface gain enough energy to overcome intermolecular forces
Volatility
measure of evaporation rate
depends on temp & intermolecular forces
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4. A. Phase Changes temp volatility IMF volatility Boltzmann Distribution
# of Particles
volatility
IMF
volatility
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Kinetic Energy

5. A. Phase Changes Equilibrium
trapped molecules reach a balance between evaporation & condensation
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6. A. Phase Changes temp v.p. IMF v.p. Vapor Pressure
pressure of vapor above a liquid at equilibrium
p.478
v.p.
depends on temp & IMF
directly related to volatility
temp
temp
v.p.
IMF
v.p.
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7. A. Phase Changes Patm b.p. IMF b.p. Boiling Point
temp at which v.p. of liquid equals external pressure
depends on Patm & IMF
Normal B.P. - b.p. at 1 atm
Patm
b.p.
IMF
b.p.
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8. A. Phase Changes IMF m.p. Melting Point equal to freezing point
Which has a higher m.p.?
polar or nonpolar?
covalent or ionic?
polar
ionic
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9. A. Phase Changes Sublimation solid  gas
v.p. of solid equals external pressure
EX: dry ice, mothballs, solid air fresheners
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10. B. Heating Curves Gas - KE  Boiling - PE  Liquid - KE 
Melting - PE 
Solid - KE 
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11. B. Heating Curves Temperature Change change in KE (molecular motion)
depends on heat capacity
Heat Capacity
energy required to raise the temp of 1 gram of a substance by 1°C
Water has a high heat capacity
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12. B. Heating Curves Phase Change change in PE (molecular arrangement)
temp remains constant
Heat of Fusion (Hfus)
energy required to melt 1 gram of a substance at its m.p.
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13. B. Heating Curves Heat of Vaporization (Hvap)
energy required to boil 1 gram of a substance at its b.p.
usually larger than Hfus…why?
EX: sweating, steam burns
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14. C. Phase Diagrams
Show the phases of a substance at different temps and pressures.
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15. Phase diagram
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16. I. Physical Properties (p. 450-455)
Ch Gases
I. Physical Properties (p )
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17. A. Kinetic Molecular Theory
Particles in an ideal gas…
have no volume.
have elastic collisions.
are in constant, random, straight-line motion.
don’t attract or repel each other.
have an avg. KE directly related to Kelvin temperature.
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18. B. Real Gases Particles in a REAL gas… have their own volume
attract each other
Gas behavior is most ideal…
at low pressures
at high temperatures
in nonpolar atoms/molecules
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19. C. Characteristics of Gases
Gases expand to fill any container.
random motion, no attraction
Gases are fluids (like liquids).
no attraction
Gases have very low densities.
no volume = lots of empty space
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20. C. Characteristics of Gases
Gases can be compressed.
no volume = lots of empty space
Gases undergo diffusion & effusion.
random motion
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21. D. Temperature
Always use absolute temperature (Kelvin) when working with gases. ºF ºC K
-459 32
212
-273
100
273
373
K = ºC + 273
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22. E. Pressure
Which shoes create the most pressure?
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23. E. Pressure Barometer measures atmospheric pressure Aneroid Barometer
Mercury Barometer
Aneroid Barometer
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24. E. Pressure Manometer measures contained gas pressure U-tube Manometer
Bourdon-tube gauge
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25. E. Pressure KEY UNITS AT SEA LEVEL 101.325 kPa (kilopascal) 1 atm
760 mm Hg
760 torr
14.7 psi
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26. Standard Temperature & Pressure
F. STP
STP
Standard Temperature & Pressure
0°C K
1 atm kPa
-OR-
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27. Ch Gases
II. The Gas Laws P V T
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28. A. Boyle’s Law P V
P1V1=P2V2
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29. Boyles Law
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30. A. Boyle’s Law
The pressure and volume of a gas are inversely related
at constant mass & temp P V
P1V1=P2V2
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31. Applying Boyles Law

32. Practice Problems
What pressure will be needed to reduce the volume of 77.4 L of helium at 98.0 kPa to a volume of 60.0 L?
A mL sample of chlorine gas is collected when the barometric pressure is kPa. What is the volume of the sample after the barometer drops to kPa
A weather balloon contains 59.5 L of helium at sea level, where the atmospheric pressure is kPa. The balloon is released from a 4000m mountaintop where the pressure is 61.7 kPa. What is the volume of the balloon when it is released?

33. Answers
126 kPa
262.2 mL
97.7 L
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34. B. Charles’ Law V T
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35. B. Charles’ Law
The volume and absolute temperature (K) of a gas are directly related
at constant mass & pressure V T
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36. Example

37. Practice Problems
A sample of SO2 gas has a volume of 1.16 L at a temperature of 23°C. At what temperature will the gas have a volume of 1.25 L?
A balloon is inflated with 6.22 L of helium at a temperature of 36°C. What is the volume of the balloon when the temperature is 22°C?
A student collects a mL sample of hydrogen. Later the sample is found to have a volume of mL at a temperature of 26°C. At what temperature was the sample collected?

38. Answers
46°C (319K)
5.94 L
18°C (291K)

39. C. Gay-Lussac’s Law P T
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40. C. Gay-Lussac’s Law
The pressure and absolute temperature (K) of a gas are directly related
at constant mass & volume P T
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41. Combined Gas Law All of the gas laws can be combined into a single law
You can find the value of any one of the variables if you know the other five
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42. D. Combined Gas Law
P1V1 T1 =
P2V2 T2
P1V1T2 = P2V2T1
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43. Applying the combined gas law
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44. A sample of ammonia gas occupies a volume of 1
A sample of ammonia gas occupies a volume of 1.58 L at 22° C and a pressure of atm. What volume will the sample occupy at 1.00 atm and 0° C?
A student collects 285 mL of O2 gas at a temperature of 15° C and a pressure of 99.3 kPa. The next day, the same sample occupies 292 mL at a temperature of 11° C. What is the new pressure of the gas?
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45. Answers
1.44 L
95.6 kPa
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46. Avogadro’s principal One mole of any gas occupies a volume of 22.4 L
Given that the mass of a mole of gas is the molecular mass expressed in grams
Avogadro’s principal allows you to interrelate mass, moles, pressure, volume and temperature for any sample of gas
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47. Applying Avogadro’s principal
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48. Applying Avogadro’s principal
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49. Practice Problems
How many moles of acetylene (C2H2) gas occupy a volume of 3.25 moles at STP?
Determine the volume of 12.3 g of formaldehyde gas (CH2O) at STP
What is the volume of kg of helium gas at 36°C and a pressure of 98.7 kPa
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50. Answers
0.145 mol
9.18 L
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51. The Ideal Gas Law
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52. Applying the gas law 2
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53. Practice Problems
What is the pressure in atm of 10.5 mol of acetylene in a 55.0 L cylinder at 37°C?
What volume does mol of H2 gas occupy at 25°C and 1.11atm of pressure
A sample of carbon monoxide has a volume of 344 mL at 85°C and a pressure of 88.4 kPa. Determine the amount in moles of CO present.
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54. Answers
4.86 atm
5.45 x 10-4 mol
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55. Using Mass with the Ideal Gas Law
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56. Determining the Molar Mass
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57. Practice Problems
A mL sample of a noble gas collected at 88.1 kPa and 7°C has a mass of g. What is the molar mass of the gas. Identify the sample
A sample of gas is known to be either H2S or SO2. A 2.00 g sample of the gas occupies a volume of 725 mL at a temperature of 13°C and a pressure of kPa. What are the molar mass and the identity of the gas?
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58. Answers
40.0 g Argon
64.1 g/mol Sulfur dioxide
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59. Gas Stoichiometry
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60. C. Johannesson