# Warm-up Josie wants to find out if beeswax candles burn faster than regular candles. What is the independent variable? The dependent variable? Max wants.

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Warm-up Josie wants to find out if beeswax candles burn faster than regular candles. What is the independent variable? The dependent variable? Max wants to test the speed of a motor with a 9 volt battery and a 24 volt battery. What is the independent variable? The dependent variable?

Heat (SOL 7) Chapter 2, pages 50-56 (change of state)
and Chapter 4 (kinetic theory of matter, temperature scales, thermal expansion, energy flow, convection, conduction, radiation)

HEAT!! And change of state
The speed at which atoms move is called? Kinetic Energy!

If the pressure stays the same, Everything expands when heated and shrinks (contracts) when cooled
Except Water!!! Water expands when it cools!!!!

Kinetic Theory of Matter
Matter is made up of particles which are in continual random motion.

Temperature Measures Motion
Motion of atoms and molecules affects an object’s state of matter (solid, liquid, gas) and its temperature. Fast motion = high temperature; Slow motion= low temperature cold liquid hot liquid

Temperature Temperature is the
Measurement of how fast molecules are moving. Adaptive curriculum temperature

Celsius – the SI unit for temperature
0 is freezing point of water (at sea level) 100 is boiling point of water (at sea level) Do I have to know this? YES!!!

Farenheit Freezing is 32 degrees Boiling is 212 degrees.
Do I have to know this? NO!!!

Kelvin Freezing point is 273 Boiling point is 373
Why these crazy numbers? Because in the Kelvin scale 0 = absolute zero. The temperature at which all matter turns solid. (freezes) and motion stops. Do I have to memorize these numbers? NO!!!!

No Motion = Not Possible
Show PSA – Heat and Temperature .mov

No Motion = Not Possible
Absolute Zero is a theoretical point where all molecular motion is stopped. It is -273 degrees Celsius It is at 0 degrees Kelvin It is at -456 degrees Fahrenheit . Show PSA – Heat and Temperature .mov

Temperature Game

How does a thermometer work?
When something becomes hot, it’s molecules move faster and take up more space. (It expands). When the liquid in a thermometer gets hot it expands and moves up!

How it works

Moving atoms move atoms
The transfer of this motion of atoms/molecules is called HEAT. This energy flows from where it is HOT to where it is NOT. Even cold things have heat energy! What is an example of heat going from where it’s hot to where it’s not? Adaptive Curriculum – Heat Conduction– (Aka – Pans on a Stove) Adaptive Curriculum – Heat Transfer – Heat Conduction of Different materials ( AKA - Get Aliens out of Ice) Do Lab – Physics Quest – Melting Hershey Kisses by placing them on different types of metal sticks and place in hot water. Lab – Physics Quest – Convection of heat using birthday candles to make small pie tin move on a pencil. Link = Bill Nye Heat ice heat

How do hats and gloves work?

Matter Can Exist in Different States: ENERGY, Pressure & Volume
PHET change of state

Properties of Water Water coheres, which means water molecules are atrracted to each other. Why? Because one end of a water molecule has a positive charge And the other end has a negative charge so there is magnetic attraction.

Coheres – sticks to itself Causing Surface Tension

THAT’S A FACT ---- Water is the only substance that can be found as a solid, liquid and gas at normal surface temperatures on Earth.

Change of State When a substance changes state (solid, liquid, gas) it’s identity does not change and the process can be reversed. All three of these Pictures are of iron in different States.

Warm-up What holds more heat – a glass of water or a lake (if they are at the same temperature) What is the name for the process by which a liquid becomes a solid? What is the SI unit of measurement for temperature? In the heating curve on the right, what is the boiling point temperature? What letter is the melting point? What letter represents a gas? What is the freezing point? What is the condensation point? What is the difference between Conduction and convection? 10. What is absolute zero?

Change of State: Heating matter
ADD ENERGY (heating) and atoms can speed up enough to change state: Melting – solid changes to liquid. The temperature at which this happens is the “melting point”.

Why doesn’t wood melt? Some things burn before they melt
Heat of combustion is lower than the melting point. (Combustion is the temperature at which something burns).

Vaporization – a liquid is heated and turns to a gas

Two kinds of vaporization:
1. Evaporation occurs only at the surface of a liquid.

2. Boiling is vaporization that occurs throughout a liquid.
**Boiling point is the temperature at which boiling begins.

Matter Brainpop-States of Matter
Freeze popcorn kernals in butter. Place into a a beaker on a hot plate. Warning – hot popcorn will fly. Ask – what state of matter is this? Solid When heated- what state is it turning into? Why does the graph show a flat line?? (when changing phase all energy goes toward making the change and moving atoms further apart. The temp. does not change during a phase change.) What happens to the butter when the kernals pop – it changes to a gas. How would you describe the energy change when turning to a gas? Have kids eat the popcorn and write in science journal about phase changes and energy. Adaptive Curriculum- Melting and Boiling Points – Heating Curves Heating Curves Activity. Print off Student Worksheet at the bottom. Teacher’s Domain Video Heat Fusion of Water -

Sublimation – solid turns to a gas (no liquid phase)

Change of State (Cooling)
REMOVE ENERGY (cooling) and atoms move slower, this can cause a change of state Condensation – a gas becomes a liquid. Freezing – A liquid becomes a solid.

Cooling Curve

Heating and Cooling curves on the same graph

What Determines the State of Matter?
Energy of the Atoms (measured as Temperature) Pressure on the Atoms Volume – The amount of space the atoms are given. Have kids fold a paper hot dog style and put PTV on it. Ask, what happens if I increase the pressure…volume decreases. What is temperature goes up? Click Pressure to go to classzone and explore PTV interactions. Use pressure pullers to boil water.

Thermal Expansion When an object is heated, its atoms move faster and take up more space so the size of the object expands Water is the exception. It gets smaller when heated and larger when frozen

Asphalt

Warm-up What do you think holds more heat? Which would be easier to increase or decrease the heat of? Why? Which of these heats up Faster? Why Rubber tire Copper Cube

Heat . . . Large substances hold more heat than smaller substances and it’s more difficult to change their heat. Specific heat – The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. What substances do you think have a high specific heat? A low specific heat?

Atom Motion is Transferred

Convection Currents Heat moves from where it’s hot to where it’s not
Because hot fluids and gases are LESS dense than cold fluids and gases, they rise. Cold sinks Hot rises

Convection Currents

Earth’s Energy Budget 50% absorbed by earth’s surface
19% absorbed by the atmosphere and clouds 20% reflected by the clouds 4% reflected by the earth’s surface 6% reflected by the atomosphere

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