58606584 Science Form1 Chapter 7

8/10/2019 58606584 Science Form1 Chapter 7

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Chapter 7HEAT


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7.1 Heat as a form of energy

Heat is ________________. The SI unit is __________

When heat energy is supplied to a substance, the _______________

of the substance will _________.

Heat flows from a _________ to a _______ place. This process of

heat transfer will stop when the temperature of the 2 places

become _____________.

Sources of heat:

Burning

Friction

Electricity

The mantle of the Earth


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Use of heat:

drying

ironing

cooking

keeping warm

Temperature Temperature is the________________ of hotness or coldness of an object.

A thermometer is used to measure temperature. The SI unit of temperature

is the _________________ However, the commonly used unit is

______________

__________ substances have ____________________ whereas ________

substances have ____________________ .


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4) The difference between heat and temperature:

Heat

A form of energy

Can do work

SI unit = Joule (J)

Temperature

A measure of the

hotness or coldness ofan object

Cannot do work

SI unit = kelvin (K)


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5) 3 types of thermometers:

Type ofthermometer

Mercuryin glass

laboratorythermometer

Clinicalthermometer

Alcoholin glassthermometer

Rangetemperature

-10 0C and 110 0C

35 0C and 42 0C

-117 0C and 78 0C

Use

Measures

temperature whendoing experiments

Measures bodytemperature

Measures very lowtemperatures


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Is heated

Particles _______ heat

Particles receive energyand move_______

The distance betweenthe particles _______

The volumeof thematter _______

The matter _______

Is cooled

Particles _______ heat

The particles lose energyand move more_______

The distance betweenthe particles _______

The volumeof the matter_______

The matter _______

Matter7.2 The effectof heat flow

on matter


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Expansion and Contraction (Solids)

1) A solid _______ when it is heated. It _______ when it is cooled.

2)The expansion of solid can be shown by a metal ball.


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3) Different metals expand at different rates:

Aluminium

Brass expansion

increases

Copper

Iron


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4) Different metals expand unequally when heated to the sametemperature. This can be explained by heating ______________

Brass

Iron

Heated

* When heated, showing that ________ expands more than ______

Heated

* When heated, showing that __________expands more than__________

Aluminium

Copper


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Expansion and Contraction (Liquids)

1) A liquid _______ when it is heated. It _______ when it is

cooled.

2) Different liquids expands and contract at difference rates

Benzene

Alcohol

increases

Water expand

Mercury


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Expansion and Contraction (gases)

Gases _______ when it is heated and _______ when cooled.

Different gases expands at the same rate.

Transfer of Heat

Heat can be transferred from a hot to a cold place by theprocess of

a) Conduction

b) Convection

c) Radiation


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CONDUCTION

1) Conductionis the transfer of heat energy between neighboring

molecules in a substance. It takes place from a region of

___________________to a region of ________________________________________________

2) When one part of an object is heated, its get hot. The particles there

gain heat energy making them vibrate stronger. They then collide and

pass some heat energy to the neighbouring particles.

Iron rod

Heat transfer
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CONVECTION

1) Convection is the transfer of heat in fluids (liquids and gases) carried

out by moving particles.

2)______fluidsbecome less dense and move upwards.

______fluidsthat are densermove down to replace the hot fluids.

3) A convection current is produced.

Convection in liquid


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RADIATION

Radiation is the transfer of heat without involving a medium.

Radiation can take place through air space or a____________.

Radiation heat moves at the speed of_________.

Radiation heat can be absorbedor reflected


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Conduction

Solid

Heat is transferfrom particle toparticle through

vibration

Convection

Fluid (liquid orgas)

Heat is broughtby the heatedparticles that

move upwards

Radiation

Solid, liquid or gas/ no medium

Heat moves in theform of waves in a

straight line

Comparison between conduction,

convection and radiation

Medium

Take place inVacuum

Speed

Way heat istransfer


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2) SEA BREEZE

Sea breeze blow during the______.

During the day, the______heats up faster than the______.

The air on surface of the land become warm(less dense) and______

The cooler air over the sea (denser)______in to take place of the

warm air.


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HEAT CONDUCTOR

Substance that conduct heat are called __________________.

Some substances conduct heat readily(good heat conductor)

All metal such as iron, magnesium, aluminium and zinc are good

____________of heat.

Copper

Aluminium

Brass best conductor

Zinc

TinIron

Lead


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Uses of heat conductors

Cooking utensil ( kettles, pots, pans) aremade from metals. Food can be cooked

quickly or water can be boiled quickly.

Mercury in the bulb expands

and contracts easily.

The bottom of an electric iron is

made up of metals so that it can

heat up quickly
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HEAT INSULATOR

Substance that conduct heat poorly are called insulators

Non-metal such as glass, wood, cork, air, water and wool are insulators.

Fluids (liquid, gas) are poor conductors of heat.

Uses of heat insulators.

Handles of kettles, irons and

cooking utensils such as pots andfrying pan are made of wood

or plastic


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Application of the principle of convectionin daily life

Ventilation of building

a. The hot air in the building will flow out through theventilation holes at the top.

b. The cold air enters through the holes (windows/door) on the lowerpart.

2) Refrigerator

a) Cold air from the freezer compartment at the top moves downto the lower part of the refrigerators. The hot air is moved up.

3) The cooling system in a car(radiator of the car)a) The water around the engine becomes hot when the engine

moves. Hot water flows up through the radiator and getscooled. The cold water moves down and flows back around theengine.

7 3 Eff t f H t M tt


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7.3 Effect of Heat on Matter

1) Matter exists in solids, liquids and gases. Matter can change from one

state to another.Eg: Solidcan be change to a liquidby heating. (heat absorb)

A liquidstate can be change to a solidby cooling. (heat release)

Sublimation

Sublimation

Liquid

GasSolid

e c ange n e s a e o


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e c ange n e s a e omatter.

Process

Condensation

Melting

Freezing

Evaporation/Boiling

Sublimation

Sublimation

Change in stateAbsorb/ release

heat


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CHANGE IN STATE OF MATTER DAILY LIFE

1) Wet clotheswhen wet clothes dry in the sun, the water in the

clothes evaporate. 2) Puddles of water - After a rain, there are puddles of water on the

ground. When the sun come out, these puddles

evaporate.

3) Ice cubes

Ice cube can be prepared by freezing water under lowtemperature.

4) Moth ballMoth ball become smaller because of the process of

sublimation.

5) Rainwater - Water vapours in clouds condense to form rainwater.


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7.5 : Absorbing and Giving Out Heat

Good heat absorberand emitter

Bad heat absorberand emitter

58606584 Science Form1 Chapter 7

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