solids liquids gases. burn sugar (ring-stand) or melt chocolate ask students why they smell what...
TRANSCRIPT
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Kinetic Theory of Matter
• All matter is made up of atoms and molecules that act like tiny particles. These tiny particles are always in motion.
Gas Law Assumptions
1. The particles in a gas are considered to be small hard spheres with an insignificant volume. (lots of empty space and electrical attraction is nil).
2. The motion of the particles in a gas is rapid, constant and random
3. The collisions between gas particles is elastic.
Newton’s Cradle
• Elastic vs Inelastic Collisions
• Elastic: kinetic energy is transferred without loss from one object to another in a collision.
• Is the collision elastic or inelastic?
• Measurements indicate that the average speed of oxygen molecules in 20°C air is an amazing 1700km/h. At this speed, the odor from a hot cheese pizza in Washington, D.C., should reach Mexico city in about 115 minutes.
• Why don’t we smell food from Mexico?
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Bulb Thermometer Temperature
• How hot or cold something is (Colloquial definition)
• The average speed (kinetic energy) of the particles in a substance. (Scientific)
• ↑ Speed = ↑ Temperature
• ↓ Speed = ↓ Temperature
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What Happens if I add a drop of food coloring to a glass of hot and cold water?
Hot Water Cold Water
9
White Board Brainstorm
• What are the three states of matter?
• Tell me something about each state of matter?
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SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Volume
Particle Motion
Arrangement
Picture
12
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Volume Definite Volume. Not compressible.
Particle Motion
Arrangement
Picture
13
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Volume Definite Volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
Arrangement
Picture
14
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Volume Definite Volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
ArrangementVery close together
in an orderly arrangement
Picture
15
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Volume Definite Volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
ArrangementVery close together
in an orderly arrangement
Picture
16
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container
Volume Definite Volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
ArrangementVery close together
in an orderly arrangement
Picture
17
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
ArrangementVery close together
in an orderly arrangement
Picture
18
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)
ArrangementVery close together
in an orderly arrangement
Picture
19
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Picture
20
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Picture
21
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container Fills a container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Picture
22
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container Fills a container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Indefinite volume. Easily compressible
(e.g. a balloon)
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Picture
23
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container Fills a container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Indefinite volume. Easily compressible
(e.g. a balloon)
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)Move rapidly with very high energy.
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Picture
24
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container Fills a container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Indefinite volume. Easily compressible
(e.g. a balloon)
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)Move rapidly with very high energy.
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Particles are very far apart.
Picture
25
SOLID LIQUID GAS
Shape Rigid with a definite or Fixed Shape.
Takes the shape of its container Fills a container
Volume Definite Volume. Not compressible.
Definite volume. Not compressible.
Indefinite volume. Easily compressible
(e.g. a balloon)
Particle MotionParticles Vibrate but are generally locked
into place.
Particles slide past one another (liquids
can flow)Move rapidly with very high energy.
ArrangementVery close together
in an orderly arrangement
Close together but not locked into an
orderly arrangement.
Particles are very far apart.
Picture
26
Student Demonstration
• Pretend you are a tiny particle and demonstrate the motion of atoms and molecules in a solid liquid and gas.
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Hamper with Wet Clothes
• What Happens if you try to stuff wet clothes inside to make more room.
• Use this analogy to explain the volume of solids, liquids and gases.
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Liquid Party!
• As a Liquid, water molecules slide around one another and move freely. They dance and are very happy, maybe a bit terrified at times but who really knows for sure.
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Gas can really clear a room!
• As a gas H20 is very sad. All of its friends are very far away and it is very lonely.
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Changes of State
• Freezing Point: temperature at which liquid becomes a solid (Water = 0°C)
• Boiling Point: temperature at which liquid becomes a gas (Water = 100°C)
• Melting Point: temperature at which a solid becomes a liquid (Ice = 0°C)
• Are changes of state chemical or physical changes?
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Evaporation: When a liquid turns into a gas
Steam is High energy H20 gas Sweating is a cooling process
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Condensation: when gas turns into a liquid
Water forms outside a glass filled with ice and water.
Bathroom mirror after showering or a car windshield.
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Sublimation: when a solid turns directly into a gas
Dry Ice or Carbon Dioxide (CO2) turns directly into gas.
Deposition is the opposite of sublimation. Gas solid. This is how precipitation (snowflakes) forms in clouds.
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What Happens if I put a balloon over an Erlenmeyer Flask and put it on a hot plate/burner? Why?
Erlenmeyer Flask Balloon
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What Happens if I put a balloon over an Erlenmeyer Flask with already boiling water? Why?
Erlenmeyer Flask Balloon
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Volume and Temperature
• When you heat a substance the particles move faster and the amount of space they take up increases.
• We saw this with the balloon and Erlenmeyer flask on a hot plate.
What is another word for the amount of space and object takes up?
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Volume and Temperature
• When a substance cools the particles move slower and the amount of space they take up decreases.
• When cooled an inflated balloon returns to where it originally started as the particles slow down.
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What happens to basketball when it gets cold?
• The air molecules inside the ball move slower and this lowers the outward pressure and the ball deflates and loses its bounce.
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Solid Block
Heat
The Solid Expands
The mass stays the same but its volume increases.What happens to the density of the object?
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D = M/V
• If a solid object has a mass of 24g and a volume of 12cm3, what is its density and what will happen if it is heated?
• If the object expands to a volume of 16cm3 while being heated, what is its mass and what is its new density?
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Summary
• Density Decreases as Temperature Increases
• Density Increases as Temperature Decreases
• Substances Expand when Heated
• Substances Contract when Cooled
T↑ V↑ D↓ T↓ V↑ D↑
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Violating Kinetic Theory
• What happens if you put a can of soda in the freezer and leave it there?
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Violating Kinetic Theory
• Shouldn’t it contract (get smaller) as it cools?
• Why does it expand and explode?
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Violating Kinetic Theory
• Ice is colder than liquid water so shouldn’t it be more dense and sink?
• Does Ice Sink in water?
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Water is an Exception!!!!
• Water is one of the few known substances that doesn’t always contract as it gets colder.
• Water behaves normally most of the time but between 0°C and 4°C it behaves oddly.
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Peculiar H20
• Water at 4°C will EXPAND when cooled until 0°C at which point it becomes ice.
• Likewise, as Ice at 0°C melts it CONTRACTS as it turns into a liquid.
• Outside of this narrow range, water behaves normally but this is why soda left in the fridge explodes!
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(-20°C)---------(0°C)---(4°C)---------------------------------(100°C)
Water behaves oddly between 0
and 4C
Water behaves normally and contracts when cooled and expands when heated.
THIS IS VERY IMPORTANT FOR LIFE AS WE KNOW IT!!!!