1. Chapter 14: Solids, Liquids, and Gases
Section 1: Matter and Thermal Energy
Section 2: Properties of Fluids
Section 3: Behavior of Gases

2. Section 1: Matter and Thermal Energy
States of matter
Kinetic Theory – an explanation of how particles in matter behave
4 assumptions:
all matter is composed of small particles
the particles are in constant, random motion
these particles are colliding with each other and the walls of their container
the amount of energy that the particles lose from these collisions is negligible
Thermal energy – the total energy of a material’s particles
Includes KE – the motion of the particles
Includes PE – the force that acts within or between particles
Average KE – a measure of the hotness or coldness or a material (temperature)
Thermal expansion – the increase in the size of a substance when the temperature of the substance is increased
Expansion and contraction can occur in most solids, liquids, and gases
Water is the exception to thermal expansion
Water expands when it changes state from a liquid to a solid

3. Section 1: Matter and Thermal Energy
States of matter
The four states of matter:
Solid – has a definite volume and definite shape
particles are closely packed together
most solids have a specific geometric arrangement
Liquid – has a definite volume and assumes the shape of its container
particles in the material slide past one another (flow)
the attractive force between particles is less
particles have higher KE than those in a solid
melting point: the temp. at which a solid begins to liquefy
heat of fusion: the amount of energy required to change a substance from the solid phase to the liquid phase
Gas – no definite volume or shape
particles of a substance are moving very fast
no attractive force between the particles
boiling point: the temp. at which the pressure of a vapor is equal to the pressure of the atmosphere
heat of vaporization: the amount of energy required for the particles to overcome the attractive forces within the liquid (energy required to change from a liquid to a gas)
Plasma - a gas consisting of positively and negatively charged particles
99% of the matter of in the universe is in this state
all the stars are plasma, as are lighting bolts and auroras

4. Section 2: Properties of Fluids
A fluid is any material that flows – liquids and gases are fluids 
Buoyancy – the ability of a fluid to exert an upward force on an object immersed in the fluid
Archimedes Principle – the buoyant force on an object is equal to the weight of the fluid displaced by the object, or:
Example 1: A piece of glass, its volume = 0.05-m3, is placed in a container of seawater. What is the buoyant force acting on the piece of glass
Solution
Where:
FB = buoyant force (N)
ρ = density (kg/m3)
V = volume (m3)
g = acceleration due to gravity (9.8 m/s2)

5. Section 2: Properties of Fluids
Example 2: Will the glass from example 1 float in the seawater or will it sink? Look at the graphic to the right . Notice the two forces acting on the piece of glass. If we can calculate the weight of the piece of glass we can then compare it to the buoyant force acting on the glass. If the weight is greater than the buoyant force it will sink, if the weight is less it will float. Here is a new equation for weight: Solution FB = N, W = 1,274-N. The glass will sink
𝑾=𝝆𝑽𝒈
Where:
Ρ = the density of the object immersed in the fluid
V = the volume of the object
g = acceleration due to gravity (9.8m/s2)

6. Section 2: Properties of Fluids
Pascal’s Principle – pressure applied to a fluid travels through the fluid
Pressure – force per unit volume
Hydraulics – the use of pressure in fluids to do work
Hydraulic lift – a machine that moves heavy loads in accordance with Pascal’s Principle
Example: a car lift at a garage A pipe filled with fluid connects a cylinder with a small diameter to a cylinder with a large diameter 1) pressure is applied to the small cylinder and is transferred through the fluid 2) because the pressure remains constant throughout the fluid, more force is available in the larger cylinder
Example: a hydraulic lift applies a force of 2,500-N to a piston with an area of 5-m2. The resulting pressure is transferred to a cylinder with a 7.5-m2 piston. What is the force acting on the 2nd piston?
Solution

7. Section 3: Behavior of Gases
Pressure
Gas particles are constantly moving and colliding with anything in their path
The collision of gas molecules in air result in atmospheric pressure
Pressure – the amount of force exerted per unit area, or:
Pressure is measured in units pascals (Pa)
1-Pa = 1n/m2 → a very small unit
Most pressures are expressed as kilopascals (kPa)
At Earth’s surface (sea level) pressure = 101.3kPa
In containers (ex.: a tire) the gas molecules collide with the container’s wall resulting in pressure being applied to the walls

8. Section 3: Behavior of Gases
The Gas Laws
Boyle’s Law – at constant temperature, a change in volume results in a change in the pressure on the container
As volume decreases, pressure increases
As volume increase, pressure decreases
At constant temperature, the product of pressure and volume is constant, or:
So:
Example: A balloon has a volume of 10.0-L at a pressure of 101-kPa. What will the volume be if the pressure drops to 43-kPa?
Solution

9. Section 3: Behavior of Gases
The Gas Laws
Charles’s Law – at constant pressure, the volume of a gas increases as the temperature increases
Mathematically:
Example: At 293 K the volume of an inflated balloon is 5-L. Two hours later the temperature is 305 K, what is the balloon’s volume now?
Solution

10. Section 3: Behavior of Gases
The Gas Laws
Guy-Lussac’s Law – At constant volume, the pressure exerted by the gas increases as temperature increases
Mathematically:
Example: At 293 K the pressure of the gas in an aerosol can is 150 kPa. What is the pressure in the can when the temperature is 310 K?
Solution