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Heating and CoolingHeating and Cooling

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Heat and TemperatureHeat and Temperature

This cup of coffee will ____ ____ because it is _____ ____ heat energy into the surroundings.

This drink (taken out of the fridge) will _____ ___ because it is _____ ___ heat energy from the surroundings.

Heat is a type of energy that will flow from a warm area to a colder one. For example…

Words – giving out, warm up, taking in, cool down

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Heat energyHeat energyHow much heat energy an object has depends on its temperature AND how much of it there is…

The sparkler is at a higher temperature than the bath, but the bath is MUCH heavier, so it has more heat energy.

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Particle theory revisionParticle theory revisionParticle theory is all about explaining the properties of solids, liquids and gases by looking at what the particles do.

In a solid the particles ______ around a _____ position. There is a ______ force of attraction between each particle and they are very _____ together

SOLIDS

Words – strong, close, vibrate, fixed

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LIQUIDS

GASES

In a liquid the particles are _____ together but can move in any direction. They won’t keep a _____ shape like _____ do.

In a gas the particles are very far apart and move _____ in all directions. They often ______ with each other and because they are far apart they can be easily _______.

Words – fixed, collide, quickly, close, very, solids

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Heating a solidHeating a solidWhen a solid is heated it expands. We can use particle theory to explain why:

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When a solid, liquid or gas heats up it will expand.

When a solid, liquid or gas cools down it will contract.

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Changes of stateChanges of state

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Changes of StateChanges of StateWhat are these processes called? Choose from freezing, evaporating, melting, condensing

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Heating iceHeating ice

150

100

50

0

-50

Temp/OC

Time/sThis flat line shows where energy is being used to break bonds – this has to be done during melting

This flat line shows where energy is being used to push the particles further apart for evaporation

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ConductionConduction

CONDUCTION is when heat moves through a ________. Metals are better conductors of heat than plastic or wood. This is why…

These parts are made of plastic or wood:

These parts are made of metal:

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ConductionConduction

In this experiment we saw that liquid water is a poor conductor of heat. The ice cube did not melt even though the water above it was boiling.

Air is also a poor conductor of heat. This is how many types of house insulation and clothing keep us warm.

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RadiationRadiationWhen you wear a black t-shirt on a hot, sunny day you would feel ______ than if you wore white. This is because black ________ infrared radiation (i.e. heat) from the sun better than white does.

Conduction is when heat travels through a solid and convection happens in a liquid or gas, but radiation can happen through absolutely ________ because the heat is moving by ______. This is how heat reaches us from the ____.

I’m very hot!I’m cool!

Words – sun, absorbs, nothing, warmer, waves

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ConvectionConvectionConvection is all about when a gas or liquid (“fluid”) moves and carries heat with it. When the fluid is heated it ____________. This means that it will become less __________ than the colder fluid around it. Because of this the warmer fluid will try to “_______” over the colder fluid, and this is why warm air rises. This is called a convection ___________. This is how heat reaches us from the ___________ in this room.

Words to use: expands, radiators, dense, heated, current, float

Heat transferHeat transfer1) Conduction – this is when heat is passed on through a solid by vibrations of particles:

2) Convection – this is when “heated stuff” moves somewhere else and takes heat with it:3) Radiation – this is when heat is moved by “heat waves” (infra-red) – this is how heat reaches us from the sun:

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EvaporationEvaporationHeat can also be lost when water evaporates (this is how we cool off when we sweat):

This water will evaporate because the water molecules have enough energy to “escape” from the rest of the water. When they do so they will take heat with them.

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