1. Some Properties of Solids, Liquids, and Gases
Property Solid Liquid Gas
Shape
Volume
Arrangement
of Particles
definite shape shape of container shape of container
definite volume definite volume volume of container
fixed, very close random, close random, far apart
The three common phases (or states) of matter are gas, liquid, and solid
1. Gases
a. Have the lowest density of the three states of matter
b. Are highly compressible
c. Completely fill any container in which they are placed
d. Their intermolecular forces are weak
e. Molecules are constantly moving independently of the other molecules present
2. Solids
a. Dense
b. Rigid
c. Incompressible
d. Intermolecular forces are strong
e. Molecules locked in place
3. Liquids
b. Incompressible
c. Flow readily to adapt to the shape of the container
d. Sum of the intermolecular forces are between those of gases
and solids
• The state of a given substance depends strongly on conditions

2. Unusual Heating/Cooling Curve (Axes switched)

3. Boiling-
Molecules throughout the liquid have enough energy to vaporize. Happens at the boiling point temperature.

4. Microscopic view of a liquid near its surface
Evaporation-
Only the high energy
molecules escape
the surface in to the gas phase. Happens at temperatures below the boiling point.

5. Make sense of these …and rank the three types of IMFs in ascending order of strength
High Boiling Point
WEAK IMFs
High V.P.
Low V.P.
STRONG IMFs
Low Boiling Point

6. Behavior of a liquid in a closed container…
Once it’s at equilibrium, the pressure of the gas above the liquid in a closed container is called…
VAPOR PRESSURE!

7. Vapor Pressure Strong IMFs Weak IMFs
measure of the tendency for liquid particles to enter
gas phase at a given temp.
a measure of “stickiness” of liquid particles to each other
Strong
IMFs
more
“sticky”
less likely to
vaporize
In general:
LOW v.p.
not very
more likely to
HIGH v.p.
Weak
IMFs
NOT all liquids have same v.p. at same temp.

8. Heating Curves & Phase Changes
Plot of temperature change versus heat added
Phase change =
Transformation of a substance from one state of matter to another
During a phase change, adding heat does NOT change the temperature!!

9. Gas – e.g. steam
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

10. LIQUID – e.g. water some writing from Kotz (PowerPoint online)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

11. SOLID – e.g. ice
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.