1. The Nature of Liquids and Solids

2. States of Matter
Plasma - typically an ionized gas. “Ionized" refers to presence of one or more free electrons. The free electrons make the plasma respond strongly to electromagnetic fields.
GAS – form of matter that has no definite shape or volume; it adopts the shape and volume of it’s container.
Liquid – form of matter that flows, has a fixed volume, and takes the shape of it’s container.
Solid – matter that has a definite shape and volume.

3. Activities Two different activities per table For Each
Water temperature versus boiling point
Water density at and near freezing
For Each
Hypothesis
Experimental Plan/Experiment
Data
Interpretations
Conclusion Regarding Hypothesis
Supported
Not Supported
Contradicted

4. Liquids
The particles that make up a liquid are in motion just like those in a gas
Liquid particles are attracted to each other, unlike gas particles
O2 as a molecule is linear and non-polar
H2O as a molecule is bent tri-atomic and polar
Particles are still free to flow past each other

5. Kinetic Theory
The intermolecular forces of liquids contribute to the average kinetic energy of the particles
Most particles still do not have enough kinetic energy to escape into the gaseous state
The intermolecular forces also force the liquid molecules closer together, causing liquids to have a higher density than gases

6. Evaporation
The conversion of a liquid to a gas or a vapor is defined as vaporization
When such a conversion occurs at the surface of a liquid that is not boiling, the process is defined as evaporation
Only molecules with enough kinetic energy can break away from the surface of the liquid
The hotter the liquid the greater the rate of evaporation
Examples
Evaporative cooling effect of perspiration
Cloth canteen cover

7. Boiling Point
The boiling point is the temperature a twhich the vapor pressure of the liquid is just equal to the external pressure
Bubbles of vapor form throughout the liquid, starting at the surface nearest the heat source, rise to the surface and escape into the air.
The average kinetic energy is the same for the liquid and the vapor, same temperature, but the potential of the steam is much higher – can do more work or cause more damage (burns to skin from hot liquid vs. vapor)

8. Normal Boiling Point
Then normal boiling point is defined as the boiling point of a liquid at a pressure of kPa.
Using other units – one atmosphere, 760 mm Hg, 14.7 psi
The normal boiling point of water is 100oC
Devices that take advantage of the relationship between boiling temperature and surrounding pressure
Pressure cookers
Autoclaves – used to sterilize medical instruments
Steam boilers

9. Example of Super-Heated Steam Boiler

10. Determining Normal Boiling Points for Several Substances
Vapor Pressures (kPa) of Several Substances at Various Temperatures
OoC
20oC
40oC
60oC
80oC
100oC
Water
0.61
2.33
7.37
19.92
47.34
101.33
Ethanol
1.63
5.85
18.04
47.02
108.34
225.75
Diethyl Ether
24.70
58.96
122.80
230.65
399.11
647.87
p. 276 in text

11. Sample Problem – Figure 10.11V A P O R E S U k a
Temperature (deg C)

12. Solids
In most solids the particles are packed against each other in a highly organized manner
Particles do not flow/take on container shape
Particles vibrate about fixed points

13. Discussion
What else, besides a temperature change, will cause gas pressure to increase?

14. Melting Point The temperature at which the solid turns into a liquid
Vibrations of molecules are able to overcome the forces that hold them in fixed positions
In general, ionic solids or those that have greater polarity have higher melting points

15. Crystal Structure and Unit Cells
Atoms, ions, or molecules that make up the solid substance are arranged in an orderly, repeating, three dimensional pattern.
The smallest group of particles that retains the geometric shape of the crystal is known as the unit cell
See page 281

16. Cubic Unit Cell Examples

17. Solids of More Than One Form - Allotropes

18. Amorphous Solids Some lack an ordered internal structure
Rubber, plastic, and asphalt
Some have cooled to a rigid state without crystallizing
Glass, does not melt at a definite temperature but gradually softens when heated

19. Amorphous Solids Some lack an ordered internal structure
Rubber, plastic, and asphalt
Some have cooled to a rigid state without crystallizing
Glass, does not melt at a definite temperature but gradually softens when heated