Transcript States of Matter

There are four states of matter…
Solids
Liquids
Gases
Plasmas
Fluids are materials that
Flow and have no
Definite shape of their own.
Pressure is a measure of how
Much force is applied per
Unit area.
OR…
F
P=
A
The SI unit for pressure is N/m2
This is also called the Pascal (Pa).
The Pascal unit is very small.
It is so small that the average
Air pressure here is about
1.01 X 105 Pa!!
The force exerted by a gas
Can be understood by using the
Kinetic-Molecular Theory…
This theory states that gases are
Made up of very small particles;
These particles are in constant
Random motion;
And the forces that are exerted by
The particles hitting the container
Are the cause of gas pressure.
A woman weighs 495 N and is
Wearing shoes that cover an
Area of 412 cm2. What is the
Average pressure that her shoes
Exert on the floor?
P = 1201.5 Pa
A gas is very similar to a liquid.
A gas has low density,
Density depends on pressure,
And expands to fill container
The ideal gas law relates
Gas volume, pressure, and
Temperature.
You may have seen it like
This in Chemistry…
PV = nRT
R = proportionality constant
= 0.08206 L atm K -1 mol -1
P = pressure in atm
V = volume in liters
n = moles
T = temperature in Kelvins
That formula can be rearranged
To look like this…
P1V1
T1
=
P2V2
T2
This is most useful when
Solving problems.
Helium is in a container being
Compressed. The initial volume,
Pressure, and temp are: 15L,
2 atm, 310K. If the volume
Is decreased to 12L, and the
Pressure is increased to 3.5 atm,
Find the final temperature.
T2 = 430 K
Plasma is the gas like state
Of matter made up of positively
Charged ions or negatively
Charged electrons or a mixture
Of them.
This is another fluid
state of matter.
You have all seen plasma…
Plasma exists everywhere,
Stars, lightning, neon signs, etc.
The main difference between a
Gas and plasma is that a gas
Cannot conduct electricity and
A plasma can.
Cohesive forces are forces
Of attraction between molecules.
Surface tension is a result of
Cohesive forces, and is the
Tendency of the surface of a
Liquid to contract to the
Smallest area possible.
( a sphere)
Adhesion is the attractive force
That acts between particles
Of different substances.
(like water sticking to glass)
Capillary action is the rise of
Water in a thin tube that occurs
Because of adhesion.
An ideal fluid is a fluid that has
No internal friction or viscosity
And is incompressible.
Viscosity is the amount of
“flow” a fluid has.
The higher the viscosity, the
Slower it flows. (thicker)
So the lower the viscosity,
The faster a fluid will flow.
(thinner)
Evaporation is the escape of
particles from a liquid.
This has a cooling effect.
A volatile liquid that evaporates
Very quickly.
(many times with explosive ends)
Condensation is the process
Where particles return to the
Liquid phase. This is due to
A decrease in temperature.
Pascal’s Principle states that
The shape of any container has
No effect on the pressure of
The fluid.
Or, if a pressure is created in a
Closed container, it is transferred
Throughout the entire container.
A car weighing 1.2 X 104 N sits
On a lift with an area of 0.9 m2.
Compressed air exerts a force
On a piston to lift the car. The
Area of the piston is 0.2 m2. How
Much large is the force needed
To lift the car?
F = 2.7 X 103
When you are swimming, you feel
The pressure of the water
Increase as you dive deeper. This
Pressure is a result of gravity,
Because of the weight of the
Water above you.
P = ρhg
P = ρhg
The pressure that a column of
Water exerts on a body is equal
To the density of the water times
The height of the column times
The acceleration due to gravity.
A reservoir behind a dam is 17 m
Deep. What is the pressure of the
Water at the base of the dam?
What is the pressure of the water
4 m from the top of the dam?
The buoyant force is a force
That acts upward on an object
Submerged in a liquid or
Floating on the liquid’s surface.
It was first discovered by
Archimedes.
Archimedes’ principle is as follows..
Any object completely or partially
Submerged in a fluid
Experiences an upward buoyant
Force equal in magnitude to
The weight of the fluid
Displaced by that object.
A floating object cannot be
Denser than the fluid
In which it floats.
A floating object’s buoyant force
Is equal to the object’s weight.
Fb = ρVg
A cube of aluminum (1.0 X 10-3)
Is submerged in water. The
Density of aluminum is 2.7 X 103.
What is the magnitude of the
Buoyant force acting on the metal?
What is the apparent weight of
The block?
Fb = 9.8 N Fa = 16.7 N
Bernoulli’s Principle tells us
That when the pressure in
A fluid decreases, the
Velocity increases.
This is the theory that tells
Us how an airplane flies.
Structures & Types of Solids
Crystalline Solids: highly regular
arrangement of their components
Such as table salt
Amorphous solids: considerable
disorder in their structures
(glass).
Most solids are much more
Dense than their liquid
Counterparts, water is the
Exception since it is most
Dense at 4 °C.
This is because as a liquid
Freezes its molecules fit closer
together.
Elasticity is the ability of a
Solid object to return to its
Original form after external
Forces are exerted on it.
If too much deformation
Occurs, the object will break.
Thermal expansion is the
Increase in length and volume
Of a material when heated.
This is very common, look at a
Bridge next time you drive over it,
You will see metal bands there
That connect the road.
How big those bands are dependant
On how much temperature change
There is during the year.
The amount of linear expansion
Can be found with…
ΔL = αL0ΔT
α is called the average
Coefficient of linear expansion.
There is also area expansion…
ΔA = γA0ΔT
And Volume expansion…
ΔV = βV0ΔT
A metal bar is 2.6 m long at room
Temperature, 21 °C. The bar is
Put into an oven and heated to
93 °C. It is them measured and
Found to be 3.4 mm longer. What is
The coefficient of linear expansion
Of this metal?
α = 1.8 X 10-5