States of Matter

1
Chapter 13

• States of Matter

2
Ch. 13-14 States of Matter

• Intermolecular forces give rise to properties of
  compounds.
• Physical properties of compounds in the solid
  and liquid states are determined by the types of
  atoms and the arrangement of those atoms.
• Physical properties of gases are __________ even
  if the gases have different compositions because
  they have ______________ forces of attraction
  between particles.

3
Kinetic Molecular Theory

• KMT describes behavior of gases in terms of
  ________________________
• Assumptions of Kinetic Molecular Theory
• Gas particles behave independently of one
  another. i.e.
• Gas particles are much smaller than the distance
  between them ?
• Gas particles are in constant, rapid, random
  motion
• Collisions between particles are elastic. i.e.
• All gases have the same average KE at a given
  temperature.
• (KE is directly related to the absolute
  temperature.)

4
Gas Behavior/Properties

• fluid gas particles easily flow past each
  other
• low density small mass for a large volume
  1/1000 the density of most solids liquids
• compressible able to be compressed into a
  smaller amount of space
• expandable able to be expand to the size of its
  container

5
Gas Behavior/Properties

• able to diffuse deals with the movement of gas
  particles through space
• able to effuse gas movement through a tiny
  opening (pinhole) into a vacuum.

6

• Solid Liquid Gas

7

• Solid Liquid Gas

8
Diffusion

• Diffusion rate of liquids and gases depends on
  the kinetic energy of the molecules.

9
Surface Tension
10
Water and Hydrogen Bonding
The way water hydrogen bonds as a solid causes it
to be less dense than liquid water.
11
Surface Tension
12
Soap and Intermolecular Forces

• Soap interferes with the IMF in water and ruins
  the surface tension.

13
Molar Volume

• solid nitrogen 27.2 mL/mol
• liquid nitrogen 34.6 mL/mol
• gaseous nitrogen 22,400 mL/mol
• Why are molar volumes diff. for the same element?
• They are all 28.0 g of N2 1 mole N2 6.02 x
  1023 molecules
• Did the molecule size change? _____
• What did change? _________________________

14
Molar Volume

• solid nitrogen 27.2 mL/mol
• liquid nitrogen 34.6 mL/mol
• gaseous nitrogen 22,400 mL/mol
• Do other elements have any of these same values?
• Which ones?
• Why?

15
Alcohol/Water Demo

• Why arent the volumes additive?

16
PHASE CHANGES

• solid
• liquid gas
• boiling vs. evaporation

17

• Volatile

18
Two Types of Forces

• 1)
• 2)

19
Phase Changes

• _____________ forces are broken/formed in phase
  changes.
• Bond breaking always __________ energy.
• Bond formation always _________ energy.

20
Expt. 3 Summary

• Draw a diagram of a solid that is heated until it
  is a gas.
• Solids have a definite melting point.
• Liquids have a definite boiling point.

21
Expt. 3 Summary
22
Expt. 3 Summary

• Changes in temperature correspond with changes in
  ___________ kinetic energy.
• Changes in phase correspond with changes in
  ___________ energy.
• Why doesnt the temperature change when
• a. melting a solid or vaporizing a liquid?
• _____________________________________
• b. freezing a liquid/condensing a gas?
• _____________________________________

23
Gas Pressure

• Pressure force
• Area
• gas particles exert pressure by collisions
  with the container walls
• air particles exert pressure in all directions
  atmospheric pressure

24
Barometer
25
Air Pressure Equivalents
26
Closed-End Manometer
27
Open-end Manometer
28
Gas Pressure

• Describe what will happen to the pressure of a
  gas sample if
• If temp. is ?, P ________ If temp. is ?, P
  ________
• If the volume of the If the volume of the
• container is ?, P ________ container is ?, P
  ______
• If the number of If the number of
• molecules is ?, P ________ molecules is ?, P
  _____

Pressure is always the ______________
variable. Its _____________ related to
temperature and of molecules. Its
_____________ related to volume of the container.
29
Air Pressure PV
30
Gas Laws
Boyle Law Lab Summary

• PxV ?

31
Boyles Law
32
Boyles Law

• 1) A 50.0 mL container of O2 gas has a pressure
  of 2.0 atm. What will be the pressure if the
  volume is
• a) Halved? _________
• b) Doubled? ________

33
Boyles Law

• 2) A 25.0 L sample of methane gas, CH4, is in a
  container with 3.00 atm of pressure.
• Whats the new pressure if the volume is changed
  to. . .
• 50.0 L? ________
• 12.5 L? ________
• 37.2 L? ________

34
Charles Law

• 0 C _______K
• K 273.15 C 25 C ______K
• 400 K ______C
• A sample of gas occupies 823 mL _at_ 25 C. What
  will be the new volume at 50C?

35
Charles Law
36
Gay-Lussacs Law

• 1) An aerosol can is at a pressure of 3.00 atm _at_
  25 C. Whats the pressure _at_ 47 C?

37
Gay-Lussacs Law
38
Avogadros Law
39
Avogadros Law
40
Combined Gas Law

• P V k V k P k V k
• T T n
• 1) A sample of gas occupies 25.4 L at 25C and
  2.1 atm. What volume will it occupy if pressure
  is increased to 2.4 atm and temperature is
  decreased to 0 C?

41
Gas Law Review

• Identify the law that correlates with each
  picture.

42
Gas Law Review

• A 2.91 mol gas sample occupies 35.0 L at 20.0 C
  and 2.00 atm. What is the new volume if
  temperature is doubled, volume is tripled, and
  the number of moles is halved?

43
Homework Hints

• Problem Set 3
• 1. Why does a blowout of an automobile tire occur
  most frequently when the tire is moving over
  asphalt roads in the middle of the summer?
• 2. A gas samples exerts 2.12 atm at 40C.
• a. What pressure would it exert at 80C?
• b. At what temperature would the pressure of
  this gas sample double?
• 3. A sample of gas occupies 1.25 L at 700. mmHg
  and 20 C. What pressure would it exert at 50
  C?
• 4. A gas sample occupies 5.00 L at 730. mmHg and
  20C.
• What pressure would it exert if the volume is
  doubled and the absolute temperature tripled?
• 5. A 2.0 mol gas sample occupies 4.5 L. The
  number of gas moles is increased to 3.5 moles.
  Whats the new volume?

44
Densities/Molar Masses of Gases

• Avogadros Principle equal volumes of gases (_at_
  the same temp. and pressure) contain equal
  molecules.
• molar volume
• Molar volumes of all gases ____________ _at_
  given temp. and pressure.
• Densities of all gases _______________ _at_ given
  temp. and pressure.

45
Densities/Molar Masses of Gases

• As temperature increases, molar volumes of gases
  ________.
• Q - What is the molar volume of a gas at room
  conditions - 25C, 1 atm?
• As temperature increases, densities of gases
  ______.
• Q What is the density of oxygen gas
• at STP?
• at room conditions?

46
Densities/Molar Masses of Gases

• Q Whats the molar volume of carbon dioxide at
  20C if the density is 1.83 g/L?

47
Daltons Law of Partial Pressures

• Daltons Law of Partial Pressures -

48
Daltons Law of Partial Pressures
49
Daltons Law of Partial Pressures
50
Daltons Law of Partial Pressures

• Ex. 2 A gas mixture containing 2.00 mol
  nitrogen, 1.00 mol oxygen, and 0.500 mol hydrogen
  has a total pressure of 800. mmHg. Whats the
  partial pressure of each gas?

51
Daltons Law of Partial Pressures

• Ex. 3 - A gas mixture containing 8.00 g hydrogen,
  8.00g helium, and 8.00g methane (CH4) has a total
  pressure of 2.60 atm. Whats the partial
  pressure of each gas?

52
Application of Daltons Law Collecting a gas
over water

• Q- 45.0 mL of oxygen gas is collected at 20.0 C,
  730.0 mmHg.
• Whats the partial pressure of the oxygen gas?
• What volume would this oxygen occupy at 25C, 1
  atm?

53
Ideal Gas Law

Derivation R
54
Ideal Gas LawDeriving Other Gas Laws

55
Ideal Gas Law

• What pressure, in mmHg, is exerted by 0.325 mol
  H2 gas in a 4.08 L container _at_ 35C?

56
Ideal Gas Law
2. A 1.45 mol gas sample occupies 8.77 L _at_ a
pressure of 725 mmHg. What is the temperature of
this system?

57
Real vs. Ideal Gases

• We assume that Ideal gases
• 1) Have no ________________
• 2) Have no ________________
• Thus,
• Real gases deviate from ideal behavior at
  ________ pressures and at ________ temperatures.

58
Applications of Ideal Gas LawMolar Mass and
Density

• Key Unit Analysis!
• Molar mass units
• Density Units

59
Applications of Ideal Gas LawMolar Mass and
Density

• 1) At 28C and 0.874 atm, 1.00 L of a gas has a
  mass of 1.13 g. What is the molar mass of the
  gas?

60
Applications of Ideal Gas LawMolar Mass and
Density

• 2) What is the density of a sample of ammonia
  gas, NH3, if the pressure is 0.928 atm and the
  temp. is 63C?

61
Applications of Ideal Gas LawMolar Mass and
Density

• Equation Derivations

62
Stoichiometry of Gases

• WO3 (s) 3 H2 (g) ? W(s) 3 H2O(l)
• 1) How many liters of hydrogen gas
• are needed to react completely with 725 grams of
  tungsten oxide?

_at_ 20C, 730. mmHg
63
Stoichiometry of Gases

• WO3 (s) 3 H2 (g) ? W(s) 3 H2O(l)
• 2) How many grams of tungsten are formed when
  20.0 liters of hydrogen react ?

_at_ 25C, 725 mmHg
64
Stoichiometry of Gases

• C3H8 (g) 5 O2 (g) ? 3 CO2 (g) 4 H2O(l)
• What will be the volume, in liters, of oxygen
  required for the complete combustion of 0.400 L
  of propane?
• What volume of carbon dioxide will be produced?