1. States of Matter

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

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

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

5. Phases/States of Matter
Gas
Shape of Container
Volume of Container
Solid
Liquid
ENERGY
ENERGY
Holds Shape
Fixed Volume
Shape of Container
Free Surface
Fixed Volume
Solid
In a solid the molecules are closely bound to one another by molecular forces. A solid holds its shape and the volume of a solid is fixed by the shape of the solid.
Liquid
In a liquid the molecular forces are weaker than in a solid. A liquid will take the shape of its container with a free surface in a gravitational field. In microgravity, a liquid forms a ball inside a free surface. Regardless of gravity, a liquid has a fixed volume.
Gas
In a gas the molecular forces are very weak. A gas fills its container, taking both the shape and the volume of the container

6. Some Properties of Solids, Liquids, and Gases
Property Solid Liquid Gas
Shape Has definite shape Takes the shape of Takes the shape
the container of its container
Volume Has a definite volume Has a definite volume Fills the volume of
the container
Arrangement of Fixed, very close Random, close Random, far apart
Particles
Interactions between Very strong Strong Essentially none
particles
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

7. DO NOW: Rank the following phases of matter in order from least to greatest for energy.
High Energy
Medium Energy
Low Energy
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

8. States of Matter Deposition Vaporization
Solid, Liquid, Gas are the three states of matter we will deal with.
Plasma and Neutron star are also states of matter.
For more information about plasma and neutron stars try the following links:
Coalition for Plasma Science – What is plasma?
Neutron Stars and Pulsars – Introduction

9. release energy and form intermolecular bonds
Liquids
The two key properties we need to describe are
EVAPORATION and its opposite CONDENSATION
add energy and break intermolecular bonds
EVAPORATION
CONDENSATION
release energy and form intermolecular bonds

10. Equilibrium is reached when:
Rate of Vaporization = Rate of Condensation
Molecules are constantly changing phase - dynamic
The total amount of liquid and vapor remains constant

11. Thermodynamics
Heat: the quantity of energy that flows across the boundary between the system and surrounds because of a temperature difference.
Temperature: a measure of the random motions of the components of a substance.
Heat Capacity: a measure of the amount of heat needed to change the temperature of a substance by a given amount.
Calorimetry: measure of heat flow.

12. First Law of Thermodynamics
The energy in the universe is constant

13. Calories
The amount of energy (heat) required to raise the temperature of one gram of water by one degree Celsius.

14. Heating Curve for Water
Heating curve with pictures
Create a curve!!
Heating Curve for Water
vaporization E
gas D
100
condensation C
liquid
melting
Temperature (oC)
Melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes.
Note: The temperature of a substance does not change during a phase change. B A
freezing
solid
Heat added
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 487

15. Heating Curves

16. Energy is added/ removed: q3 = mc𝚫T
Energy is used for phase change (solid to liquid): 𝚫Hf = 6.01 kJ/mol (for H2O)
[qf = m𝚫Hf]
Energy is used for phase change (liquid to gas):
𝚫Hv = kJ/mol
(for H2O)
[qv = m𝚫Hv]
Energy is added/ removed: q2 = mc𝚫T
Energy is added/ removed: q1 = mc𝚫T

17. Phase Diagrams – Definitions
Phase Diagram: a graphic way to summarize the conditions under which equilibria exist between the different states of matter
Critical Point: the point where the vapor pressure curve ends – this is the critical temperature and critical pressure of the substance
Superficial Fluid: the point where the liquid and gas phases become indistinguishable from each other (usually after the critical point)
Normal Boiling Point: the boiling point at 1 atm
Normal Melting Point: the melting point at 1 atm
Triple Point: where the three curves intersect (ie all phases exist at this specific temperature and pressure!)

20. Sample question: what changes occur as the pressure increases from 1 atm to 60 atm for CO2 at a constant temperature of -60℃?

21. Example Problem
Describe the phase changes, if any, between points 1 and 5 using the figure at the right as it relates to temperature and pressure.

22. Example Problem
Describe the phase changes, if any, between points 6 and 9 using the figure at the right as it relates to temperature and pressure.