1. Gases, Liquids, and Solids
Chemistry B11
Chapter 6
Gases, Liquids, and Solids

2. Gases
move faster
Kinetic energy ↑
T ↑

3. Gases Physical state of matter depends on: Attractive forces
Kinetic energy
Brings molecules together
Keeps molecules apart

4. Gases Gas High kinetic energy (move fast) Low attractive forces Liquid
Medium kinetic energy
(move slow)
medium attractive forces
Solid
Low kinetic energy
(move slower)
High attractive forces

5. Physical Changes
Melting
Boiling
Change of states

6. Ideal Gases In reality, There is no ideal gas (all gases are real).
Kinetic molecular theory:
Particles move in straight lines, randomly.
Kinetic energy of particles depends on temperature.
Particles collide and change direction (they may exchange
kinetic energies).
Gas particles have no volume.
No attractive forces between gas particles.
More collision = greater pressure.
In reality, There is no ideal gas (all gases are real).
At STP (Standard Temperature and Pressure): we can consider them as ideal.
T = 0°C (273 K) P = 1 atm

7. Gases Ideal gas law: PV = nRT n: number of moles (mol)
R: universal gas constant
V: volume (L)
P: pressure (atm)
T: temperature (K)
PV = nRT
T = 0°C (273 K)
P = atm
1 mole → V = 22.4 L
R = PV nT =
(1.000 atm) (22.4 L)
(1 mol) (273 K) =
L.atm
mol.K
Standard Temperature and Pressure (STP)

8. Pressure (P) Pressure (P) = Force (F) Area (A) A↓ P ↑ F ↑ P ↑
F: constant
A: constant A↓
P ↑
F ↑
P ↑
Atmosphere (atm)
Millimeters of mercury (mm Hg)
torr
in. Hg
Pascal
1 atm = 760 mm Hg
= 760 torr
= 101,325 pascals
= in. Hg

9. pressure of gas in a container
Pressure (P) Hg
barometer
atmospheric pressure
manometer
pressure of gas in a container

10. Gases Boyle’s law: m,T: constant P1V1 = P2V2 P1V1 P1V1 P2 = V2 = V2 P2
PV = a constant
P1V1 = P2V2
P1V1
P1V1
P2 =
V2 = V2 P2

11. Gases
Boyle’s law:

12. Gases Charles’s law: m,P: constant V1 V2 = T1 T2 V1T2 T1V2 V2 = T2 =
= a constant T V1 V2 = T1 T2
V1T2
T1V2
V2 =
T2 = T1 V1

13. Gases
Charles’s law:

14. Gases Gay-Lussac’s law: m,V: constant P1 P2 = T1 T2 P1T2 T1P2 P2 =
= a constant T P1 P2 = T1 T2
P1T2
T1P2
P2 =
T2 = T1 P1

15. Gases
Gay-Lussac’s law:
Pressure (P)

16. Gases combined gas law: P1V1 P2V2 = T1 T2 Avogadro’s law: n1 = n2 PV
= a constant = T T1 T2
Avogadro’s law: T1 P1 V1
P1 = P2
n1 = n2
n = number of molecules
V1 = V2 T2 P2
T1 = T2 V2

17. Gases
Dalton’s law of partial pressures:
PT = P1 + P2 + P3 + …

18. < Intermolecular Forces London dispersion forces Intermolecular
Dipole-dipole interaction
Ionic bonds
Covalent bonds
Intramolecular
(Bonding) Forces
Hydrogen bonding

19. London dispersion forces
Attractive forces between all molecules
Only forces between nonpolar covalent molecules He He He He δ- δ+ _ _ _ _ _ _ + _ 2+ 2+ _ 2+ 2+
Original Temporary
Dipole
No Polarity He He δ- δ+ δ- δ+ _ _ _ 2+ _ 2+
Original Temporary
Dipole
Induced Temporary
Dipole

20. London dispersion forces
He: T = -240°C (1 atm) → liquid
Kinetic energy ↓
Move slower
Attractive forces
become more important
T ↓
liquid

21. Dipole-Dipole Interactions
Attractive forces between two polar molecules
stronger than London dispersion forces
boiling point ↑

22. Between H bonded to O, N, or F (high electronegativity) → δ+
Hydrogen bonding
Between H bonded to O, N, or F (high electronegativity) → δ+
and a nearby O, N, or F → δ-
H2O
Stronger than dipole-dipole interactions & London dispersion forces

23. Hydrogen bonding δ+
CH3COOH
Acetic acid δ-

24. H-bonding in our body
H-bond
DNA
H-bond
Protein (α-helix)

25. Evaporation equilibrium
Vapor pressure: the pressure of a gas in equilibrium with its liquid form
in a closed container.
Boiling point: the temperature at which the vapor pressure of a liquid
is equal to the atmospheric pressure.

26. normal boiling point: the temperature at which a liquid boils under
Evaporation
normal boiling point: the temperature at which a liquid boils under
a pressure of 1 atm.
1 atm. =
760 mm Hg
Diethyl ether
CH3OH
H2O

27. Factors that affect boiling point:
1. Intermolecular forces:
London dispersion forces < Dipole-Dipole interactions < Hydrogen bonds
2. Number of sites for intermolecular interaction (surface area):
Larger surface areas (more electrons)  more sites for L.D.F  b.p.
CH3-CH2-CH2-CH2-CH >
CH3-CH2-CH3
3. Molecular shape: With the same molecular weight.
linear CH3-CH2-CH2-CH2-CH3 > spherical
CH3-C- CH3 _
CH3

28. Solids
Network solids (network crystals)
Amorphous solids

29. Solids
Solidification (Crystallization): change phase from liquid to solid.
Fusion (melting): change phase from solid to liquid.
Boiling / Vaporization: change phase from liquid to a gas
Sublimation: change phase from solid directly into the vapor.
Dry ice (solid CO2)

30. Heating Curve
Heat added (cal)
during the phase changes, the temperature stays constant.