# States of Matter: Kinetic Molecular Theory

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States of Matter: Kinetic Molecular Theory
Holt McDougal Physical Science C3S1: Matter and Energy Glencoe Science Physical Science C16S1: Kinetic Theory

NGSSS Benchmark(s) SC912P12.11 SC912P8.1
Describe phase transitions in terms of kinetic molecular theory SC912P8.1

Learning Objectives What makes up matter?
What is the difference between a solid, a liquid, and a gas? What kind of energy do all particles of matter have? How do particles move in the four states of matter? How do particles behave at the melting and boiling points of matter?

Characteristics of Matter
Has mass Has volume Made of atoms Atoms in constant motion

Kinetic Molecular Theory of Matter
All matter is made of particles that are in constant motion “Stuff is moving all the time”

Kinetic Theory 2 The faster particles move, the higher the temperature of the substance. “Fast moving stuff is hotter than slow moving stuff.”

Kinetic Theory 3 At the same temperature, more massive particles move more slowly than less massive ones. “Big stuff is slower than small stuff at the same temperature.”

What explains how particles in matter behave?
Law of Conservation of Mass Law of Kinetic Movement Kinetic Molecular Theory None of the above

What is Thermal Energy? Energy  ability to change/move matter
Total energy of the particles in a material TE = KE + PE If temperature is lowered, particles will have less thermal energy

Average Kinetic Energy
Temperature  avg of how fast particles are moving Molecules have kinetic energy at all temperatures (even absolute zero)

What two things comprise thermal energy?
Potential movement and Kinetic energy Kinetic movement and Potential energy Potential movement and Kinetic movement Potential energy and Kinetic energy

Common States of Matter
Solid, liquid, gas Definite  something does not change Variable  something can change

Solids Definite volume Definite shape
Strong attraction keeps particles in place Particle arrangement establishes chemical and physical properties

Solid to Liquid: How? Melting point  temp for solid to begin turning to liquid Particles slip out of ordered arrangement Heat of Fusion  amt of energy needed to change a substance from a solid to a liquid at its melting point

Liquids Particles faster than solids Flow freely Definite volume
Variable shape

Liquid to Gas: How? Particles have enough energy to escape attractive forces Evaporation  particles at surface & travel away Boiling point  temp at which pressure of the vapor in the liquid = external pressure on surface of liquid Heat of vaporization  amt of energy needed for liquid at its boiling point to become a gas

Gases Overcome attractive forces Variable shape Variable volume

How would you respond? What is the temperature at which a solid begins to turn into a liquid called? Which particles have the least kinetic energy? What do particles need in order to overcome the force of pressure and become a gas? How does the movement of particles in a liquid differ from the movement of particles in a solid? What causes a solid to have a definite volume and shape?

Fluid: What is it? State of matter with variable shape Liquids Gases

Plasma Matter made up of positively and negatively charged particles (i.e., ionized particles) Neutral Conducts electricity Stars, lightning bolts, neon and fluorescent tubes, auroras

Thermal Expansion Increase in the size of a substance when the temperature is increased “Hot stuff moves faster and takes up more space.”

Solid or Liquid: Which? Amorphous solid  no melting point; soft over a range of temperatures Glass Plastic Liquid Crystals  maintain ordered structure from solid to liquid state

What do you think? Describe the movement of particles in a fluid.
Is plasma a fluid? Explain your answer. Why do all particles of matter have kinetic energy? Which of the three common states of matter has particles with the most kinetic energy? Why do all particle of matter have kinetic energy? What does temperature measure?

Changes of State of Matter
Holt McDougal Physical Science C3S2: Matter and Energy

Learning Objectives What happens when a substance changes from one state of matter to another? What happens to mass and energy during physical and chemical changes?

What Causes Matter to Change States?
Change of state  from one physical form to another Caused by transfer of energy Identity of substance remains the same

Heating  adds energy Adding NRG  causes particles to move more quickly Removing NRG  causes particles to move more slowly

Temperature and Energy
Adding NRG  increases kinetic energy of the particles Removing NRG  decreases kinetic energy of the particles Temperature  measure of the avg kinetic energy

Think fast! What does “hot” mean for temperature?
What will removing all kinetic energy do to a gas?

Changes of State That Require Energy
Melting  from solid to liquid Melting point  particles have enough nrg to break from rigid positions Melting point  can change if pressure changes

Evaporation Change from liquid to gas
Boiling  evaporation at specific temp and pressure Boiling point  temp at which liquid boils

Sublimation Change from solid to gas Example: Solid CO2
–(room temp) Gas CO2

What’s Your Answer? What are three changes of state that require energy? Melting Boiling Subliming

Changes of State That Release Energy
Condensation  from gas to liquid Condensation point  temp to chg from gas to lqd Condensation  often happens when gas touches cool surface (e.g., vapor touches cold glass and becomes water droplets)

Freezing Point Freezing  chg from lqd to solid
Freezing point  temp at which substances freezes Freezing point = Melting point = Freezing point Add nrg to melt; release nrg to freeze

Do you recall? What is the condensation point?
What is the melting point? What is the boiling point? What is the point? 

What Happens to Temperature During Changes of State?
Temp  does NOT chg during a chg of state “When a substance loses or gains energy, either its temperature change or its state changes (The) two changes do not happen at the same time.” (p. 51)

html mechanics/energy/heatAndTemperature/chang esOfPhase/changeOfState.html

What Happens to Mass and Energy During Physical and Chemical Changes?
Law of Conservation of Mass Law of Conservation of Energy Conserve  to keep the same

Holt McDougal Physical Science C3S3: States of MatterFluids

Learning Objectives How do fluids exert pressure?
What causes objects to float? What happens when pressure in a fluid changes? What affects the speed of a fluid?

What Are Fluids Liquids and gases Particles can move past each other
Exert pressure in all directions

What Is Pressure With your neighbor, come up with a quick demonstration of pressure . . . Pressure  amt of force exerted on a give surface area

Is pressure a derived unit?
Calculating Pressure Divide force by area Pressure = Force/Area; P=F/A Pascal  SI unit for pressure Newton  SI unit for force 1 Pa = 1 N/m2 Is pressure a derived unit? Why/not?

Try Calculating Pressure
Given a force of 20N over 60m2, how much pressure is being exerted? Try this on your whiteboard. Write the formula: P = F / A Substitute values: P = 20N/60m2 Divide the units: P = N/m2 Now, divide the quantities: 20/60= .33 Assemble the answer: P = 0.33N/m2

What Causes an Object to Float?
Buoyant force  upward force fluids exert on matter Archimedes’ Principle  “The buoyant force of an object equals the weight of the fluid that the object displaces.”

Do you remember . . . What is pressure? What is a Pascal?
The amount of force exerted over an area What is a Pascal? The SI unit for pressure; 1Pa = 1N/m2 Given area and pressure, how does one determine the number of Newtons required? Since P=F/A, then F = P * A

Will It Sink or Float? Compare weight to buoyant force  why?
By Weight By Density Compare weight to buoyant force  why? Floats  bouyant force > or = object’s weight Sinks  bouyant force < or = object’s weight Compare density of object to density of fluid Floats  object is less dense than the fluid Sinks  object is denser than the fluid BTW, the density of water is . .. 1 g/cm3

What Happens When Pressure Changes in a Fluid?
What happens when you squeeze a balloon? What happens when you squeeze a tube of toothpaste? Pascal’s principle  “If the pressure in a container is increased at any point, the pressure increases at all points by the same amount.”

Pascal’s Principle (formula)
P(1) = P(2) If P = F / A, then what does F(1) / A(1) equal? F(1)/A(1) = F(2)/A(2) Remember, pressure is measured in pascals and 1Pa = 1N/M2

Hydraulic Devices and Pascal
Use liquids to transmit pressure from one point to another Car lift Beautician chair Barbershop

Apply Pascal’s Principle to Solve
A hydraulic lift uses Pascal’s principle to lift a 19,000N car. The area of the small pistons equals 10.5cm2 and the area of the large piston equals 400 cm2. What force must you exert on the small piston to lift the car? Write formula Substitute Do the math

Properties of Fluids in Motion
Fluids and area Fluid pressure and speed Viscosity

Fluids and Area What happens when you put your finger over the opening for a water/garden hose? If the flow rate stays the same, fluids move faster through small areas than large areas.

Bernoulli’s Principle
Swiss Scientist from 1700 to 1782 Published his discovery in 1738 Blow across top of paper As the speed of a fluid increases, the pressure exerted by the fluid decreases.

How can you use density to determine if an object will float in a fluid? You put a small object into a cup of water and the displaced water weighs 235N. What is the buoyant force on the object? Explain your answer. How does a hydraulic device multiply force? A balloon filled with helium floats in the air. What does this tell you about the density of helium? How are speed and pressure of a fluid related? How do the attractions between particles in a fluid determine viscosity?

Fluid Flow Viscosity Viscosity  fluid’s resistance to flow
Think about the principles of Kinetic Molecular Theory; why are some fluids more viscous than others? In general, the stronger the attraction between the particles of a fluid, the more viscous the fluid is.

Holt McDougal Interactive Reader Chapter 3 Section 4
Behavior of Gases Holt McDougal Interactive Reader Chapter 3 Section 4

NGSSS and Learning Objective Questions
SC912P Interpret the behavior of ideal gases in terms of kinetic molecular theory What are some properties of gases? How do changes of pressure, temperature, or volume affect a gas?

Physical Properties of Gases
What are some physical properties of Gases? Class Notes these properties: Expand to fill their containers Easily mix with one another Have low densities Can be compressed Are mostly empty space Exert pressure on their containers

Gas Laws Boyle’s Law  variable volume
Gay-Lussac’s Law  variable pressure Charles’s Law  variable temperature

Boyle’s Law Works if temperature and amount of gas are constant or unchanged “For a certain amount of gas at a constant temperature, the volume of a gas decreases as the gas’s pressure increases. Likewise, the volume of a gas increases as the gas’s pressure decreases.” P1V1 = P2V2

Practice Boyle’s Law Given a balloon with a volume of 7.5L at kPa, what is the pressure of the balloon when the volume is 11.0L? Write the formula P1V1=P2V2 Substitute values 7.5(100)=P2(11.0) Multiply 750=11.0(P2) Divide 750/11.0=11.0(P2)/11.0 Assign correct units 68kPa

Try Boyle’s Law, again A 300mL sample of H gas is at a pressure of KPA. If the pressure increases to kPa, what will be the final volume of the sample? Assume that temperature stays constant. Write the formula Substitute values Multiply Divide Assign correct units

Think About It . . . What might happen if you threw a full can of spray paint into a raging fire? remember the container is rigid, so its volume cannot increase!

Pressure and Temperature
Temperature  measure of avg kinetic nrg Increase temp  particles gain kinetic nrg and bump sides of container more often Increase temp  pressure increases

Gay – Lussac’s Law “When volume is constant, the pressure of a gas increases as temperature increases. Pressure decreases as temperature decreases.” Pressure and temperature = directly related. Change one = same kind of change in the other

Charles’s Law: It’s the Kinetic Theory!!!
A scientist named Jacques Charles did many experiments involving gas volumes and temperatures. “If gas and pressure are constant, the volume of gas increases as temperature increases.” V=Tk (where k is a constant pressure).

How Can Graphs Illustrate the Gas Laws?
Graphs show relationship between two factors Direct relationship  two variables change in the same direction Inverse relationship  variables change in opposite directions Straight line  directly proportional Curved line  variables don’t maintain ration