teaching unit

7/27/2019 Teaching Unit

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Teaching Unit

Topic : Heat

1.0 Purpose : The purpose of this topic is to give comprehend about the concept

and principle that related with the heat energy and application inreal life. The important to learn this topic is to give awareness

about various heat application in daily life.

2.0 Students Prior Knowledge

Students had already learn that :

Heat is a form of energy

The uses of heat

Can differentiate between heat and temperature Heat flow and its effects

Heat causes solid, liquid and gaseous to expand and contract

The applications of the principle of expansion and contraction of matter

To appreciate the benefits of heat flow

ar!, dull surface absorb and give out heat better than shiny surfaces

2.1 Lesson Plan 1 (Thermal Euili!rium"

2.1.1 Student Prior Knowledge

Student already learn that :

That heat is a form of energy

The meaning of temperature

ifferentiate between heat and temperature

2.1.2 #a$s To Elicit Students %deas

"redict#$bserve#%xplain

Teacher show a bottle of hot mil!. Student will predict what will happen when abottle of hot mil! is placed into a basin containing cold water.

&


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2.1.& Potentiall$ di''icult main ideas or o!ecti)es

Temperature is the measure of the degree

Heat is a measure of the amount of energy transferred from one body to

another because of the temperature difference between those bodies

Thermal equilibrium occurs when ob'ects will approach the same temperature

and in absence of loss to other ob'ects, they will then maintain a constant

temperature

2.2 Lesson Plan 2 (Latent *eat"

2.2.1 Student Prior Knowledge

Student "rior (nowledge :

Heat flow and it)s effect

%ffect of heat on matter

2.2.2 #a$s To Elicit Students %deas

*hole class question and answer session

Teacher shows a picture of ice cubes in a glass.

+ext, teacher shows a picture of a boiling !ettle.


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Students will give their ideas about heat transfer, temperature and change

of phase.

Teacher shows a concept cartoon at the beginning of the class as below :

-

%ce cu!es

+oiling water


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2.2.& Potentiall$ di''icult main ideas or o!ecti)es

uring change of phase, the temperature remains constant even thoughthere is transfer of heat.

atent Heat / Heat absorbed or the released at constant temperature during

a change of phase.

Specific latent heat / the amount of heat required to change the phase of

&!g of the substance at a constant temperature.

2.& Possi!le ,isconception

&. 0ce cannot change temperature. *hen the temperature of a boiling substance remains constant, something

is 1wrong.2

-. The bubbles in boiling water contain 1air,2 $xygen,2 or 1nothing,2 ratherthan water vapor.

3. 4ll liquids boil at &556C 7&689 and freee at 56 C 7-689.

;. Heat is a substance.


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&-. Heat rises.

&3. The !inetic theory does really explain heat transfer. 70t is recited, but not

believed.9&;. $b'ects which readily become ware 7conductors of heat9 do not readily

become cold.

&


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&.2 ,ain %dea %n -ge-ppropriate Language

&.2.1 Lesson Plan 1

&. Heat # Heat is a form of energy. Heat flows from hotter to colder ob'ects.

. Temperature # Temperature is a measure of degree of hotness of an ob'ect. # Temperature is not a measure of the quantity of heat in a substance.

# Hot substances have high temperature. Cold substance have low

temperature.

-. Thermal %quilibrium # There is no net flow of heat between two ob'ects that are inthermal equilibrium.

# Two ob'ects in thermal equilibrium have the same temperature.

3. iquid#in#gas Thermometer # The liquid in the thermometer should be seen easily. # The liquid should expand and contract rapidly over a

wide range of temperature.

# The liquid should not stic! to the glass walls of the

capillary tube.

&.2.2 Lesson Plan 2

&. Change of phase # 8our main changes of phase are melting, boiling, solidification andcondensation.

# Heat is absorbed during heating

# Heat is release during cooling

. atent Heat # Heat absorbed or the heat release a constant temperature during a

change of phase.

&.& elated realworld o!ects3 s$stem or e)ent

&.&.1 Lesson Plan 1

@oiling water


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0ce

Thermometer

&.&.2 Lesson Plan 2

Hot water 0ce

Thermometer

=


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&.4 /oncept ,ap *E-T

5as LawsSpeci'ic

Latent *eat

Speci'ic

*eat/apacit$

Thermal

Euili!rium

Temperature

Thermometer

Heating and cooling

D mcE

Change of state

8usion Faporisation

@oyle)s law

"ressure aw Charles) law

D ml

4bsolute ero

(elvin scale

concept of

measured by

during

formula

during

formula

T constant

low temperature

>


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&.6 Student Per'ormance !ecti)e

&.6.1 Lesson Plan 1

4t the end of the lesson, student are able to

i. explain thermal equilibriumii. explain how liquid in glass thermometer wor!s

&.6.2 Lesson Plan2

4t the end of the lesson, students are able to

i. state that transfer of heat during a change of phase does not cause achange in temperature.

ii. define specific latent heat 7 l 9

&.7 /entral 5uiding 8uestion

&.7.1 Lesson 1

i. what is the difference between heat and temperature Gii. what are the properties of the two ob'ect in thermal equilibriumG

&.7.2 Lesson 2

i. what is latent heatG

ii. what happens to temperature during the change of phaseG

4.0 %nstructional and -ssesment plan

4.1 Lesson Plan 1

4.1.1 Student Per'ormance !ecti)e

4t the end of the lesson, student are able toi. explain thermal equilibrium

ii. explain how liquid in glass thermometer wor!s

4.1.2 ,aterial and euipment

i. power pointii. cartoon

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4.1.& Student per'ormance tas9

i. group wor!ii. discussion

iii. experiment

4.1.4 E)aluati)e tools 'or per'ormance assessment

i. presentation

ii. oral question

4.2 Lesson Plan2

4.2.1 Student Per'ormance !ecti)e

4t the end of the lesson, students are able to

i. state that transfer of heat during a change of phase does not cause achange in temperature.

ii. define specific latent heat 7 l 9

4.2.2 ,aterial -nd Euipment

i. power pointii. thermometer

iii. ice

iv. hot water

4.2.& Student per'ormance tas9

i. group wor!

ii. discussion

4.2.4 E)aluati)e tools 'or per'ormance assessment

i. qui#complete blan! concept map

&5


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4.6 Time Line

#ee9 1 2 & 4

Time 1 2 & 1 2 & 1 2 & 1 2 &

Sub unit

3.& nderstanding

thermal equilibrium

3. nderstandingspecific heat capacity

3.- nderstanding

specific latent heat

3.3 nderstanding

the gas law

&&


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Title : Heat

earning area : nderstanding thermal equilibrium

ate : &3 4ugust 55 2

-cti)it$ 2

&. iscuss thermal equilibrium in liquid#in#glass thermometer.

. *hat is the temperature of pure melting iceG

-. *hat is the temperature of steamG

&


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Title : Heat

earning area : nderstanding Specific atent Heat

ate : & 4ugust 555L C

% >;L C

&&. The following table shows the information of three ob'ects Q, R and that are heated at the same rate.

!ect ,ass @g

Speci'ic heat capacit$ @ I 9g1H /1 %nitial temperature @H /

Q -55 -=5 ? x &5;N .< x &5> N

C 3.3& x &5;N -.-? x &5< N

3.3& x &5;N .< x &5> N

&?. *hen water is boiling, the temperature remains constant although heat is supplied

continuously." / The heat absorbed transferred to the water molecules as !inetic energy.

# The heat absorbed does wor! to brea! the bonds between the water molecules.

B # The heat absorbed does wor! when the water expands to become steam.S # The heat absorbed brea!s up the atoms in the water molecules.

*hich of the following statements are correctG

4 " and S

@ " and B

C and B ", and S

TSTS : Belating

TSTS : 4nalysing

TSTS : %valuating

TSTS : Jrouping and classifiying

-?


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5. 4n experiment was carried out to investigate the relationship between pressure, " andvolume, F of a fixed mass of gas at constant temperature.

*hich of the following graphs are correctG

4 N and ( @ N and A

C and A

N, ( and

&. The volume of a fixed mass of gas is halved when the pressure of the gas is double.

This is true if

4 no external force acts on the gas. @ the temperature of the gas remains constant. C the atmospheric pressure does not change.

. The volume of an air bubble in water is F&at a depth of &5 m and Fat a depth of ;

m. 0f the atmospheric pressure at the surface of the water is &5 m of water, what is the

ratio of F& to F G

4 3 : -

@ - : 3 C : &

& :

-. 4 flas! contains air at a pressure of &;5 !"a and temperature =LC. The flas! is then

immersed in a hot water with a steady temperature of >=LC. Calculate the value of the air pressure.

TSTS : Jrouping and classifiying

TSTS : %valuating

TSTS : Aa!ing inferences

35


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4 3= !"a

@ &; !"a C &>5 !"a

3>- !"a

3. The figure shows air trapped in a glass tube.

*hich of the following ways can increase the length of the air columnG

4 The glass tube is heated. @ The open end of the tube is inclined upwards.

C There is an increase in atmospheric pressure. The mercury is replaced with concentrated sulphuric acid.

;. *hich physical quantity is a constant in all the three gas lawsG

4 ensity

@ 4tmospheric pressure

C Aass

SE/T%; +

TSTS : 4nalysing

TSTS : Jenerating ideas

TSTS : %valuating

3&


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&. 4 student who wanted to design a coo!ing pot as shown in 8igure - chose to use

copper for the base and aluminium for the body of the pot. Table & gives values ofdensity and specific heat capacity for three types of metals.

7a9 State two advantages of using copper as the base of the pot.

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7b9 Suggest two reasons why aluminium was chosen as the material for the body of

the pot and not copper or lead.

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7c9 *hy the lead not chosen even though it has a large density and a small specific

heat capacityG

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7d9 The base of the pot is a copper disc with volume -.5 x &5#3m-. The initialtemperature of the coo!ing flame is >;5LC.

7i9 *hat is the mass of the base of the potG

,etal =ensit$ @ 9g m& Speci'ic heat capacit$ @ I 9g1H /1

4luminium =55 ?55

Copper >?55 -?5

ead && -55 &-5

3


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7ii9 Calculate the quantity of heat that is needed to raise the

temperature of the base equal to the temperature of the flame

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. Table shows the characteristics of four types of glass.

T$peo'

glass

=ensit$ @9g m&

Speci'ic heatcapacit$ @I 9g1H/1

So'tens attemperature @

H/

ate o'thermal

eJpansion

" 335 >35 ;=; Aedium

3=5 ;5- ? owB -5 =;- >& ow

S ;&5


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KKKKKKKKKKKKKKKKKKKKKKK M2 mar9sO7iii9 *hat are the variables that need to be fixed in the comparison of

change

of temperature in (a"(ii"G


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7iv9 Rou are as!ed to investigate the characteristics of the four typesof

glass in Table & which could be used to ma!e good quality bowls.

%xplain the suitability of each characteristics in Table & and hence

determine which glass is most suitable to be used to ma!e the bowls.

Nustify your choice.


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7b9 7i9 The body of a marathon runner of mass ;; !g generates >.5 x &5;N

of heat in 5.; hours. *hat is the increase in his body temperature if the

heat generated is not lost to the surroundingGM-ssume speci'ic heat capacit$ o' human !od$ &600 I 9g1H/1O


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7ii9 *hat must the runner do to ensure that his body does not

experience highincrease in temperature as in 7b97i9G

MSpeci'ic heat capacit$ o' human !od$ &600 I 9g1H/1O



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S/*E,E

SE/T%; -

& @

- @

3 C; 4

< C= 4

> @

? C&5

&& C

&

&- 4&3 4

&; C

&< @&=

&> C

&? C5 4

& @

@- C

3 4

; C

3;


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SE/T; + (1"

7a9 # High density and greater mass at the base ma!es the pot more stable. M&O

# ow specific heat capacity heats the pot faster. M&O

7b9 # ow density of aluminium reduces the total weight of the pot. M&O

# 4luminium does not react with most food substances. M&O

7c9 # ead is poisonous M&O

# High density of the lead ma!es the pot heavier even before putting in food

items. M&O

7d9 7i9 Aass D Folume x ensity M&O

D -.5 x &53x >?55

D ..;? x &5;N M&O

3


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SE/T%; + (2"

&. 7a9 7i9 The specific heat capacity of a substance is the amount of heat that must

be supplied to increase the temperature by &LC for a mass of & !g of thesubstance. M&O

7ii9 Jraph of temperature against time

MO7iii9 # Aass of the glass M&O

# 0nitial temperature M&O

7iv9

/haracteristic EJplanation

Jlass with higher density M&O The bowl will be heavier and

more stable M&O

arger specific heat temperature M&O oes not heat up very quic!lywhen hot food is put inside

the bowl. Cools down more

slowly. 8ood in bowl remainswarm. M&O

Softer at a very high temperature M&O Aaintains its shape eventhough it is very hot M&O

ower rate of thermal expansion M&O Smaller expansion when it ishot, less li!ely to brea! when

hot food is put inside it. M&O

7v9 # Jlass B is the most suitable M&O

# Jlass B has a high density and large specific heat capacity, softens at the

Highest temperature and has low rate of thermal expansion. M&O

7b9 7i9 0ncrease in body temperature D E

D E

>.5 x &5;D ;; x -;55 x E

E D 3.LC MO

3=


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7ii9 # rin! water while running. Heat will be removed from his body when hesweats. M&O

# *ear thin clothing, sleeveless shirt and short. Heat is lost to thesurroundings through the exposed parts of his body M&O

3>


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Faster rate of energy

transfer

Slower rate of energytransfer

Cold

objectHot

object

Equivalent to

Net flow of energy fromthe hot object to the

cold object

2.1.

A hot and a cold object in thermal contact

Energy transferred at

the same rate.

No net heat

transferred

3. 4.

he heat isma!ing me

sweat..

" thin! thetem#erature

is $%oC

"t&s hot

today'

3?


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hermal Equilibrium

(. wo object in thermal equilibrium have

the same tem#erature.

). he are is no net flow of heat between

two objects that are in thermal

equilibrium.$. he amount of heat energy flowing out of

one object is the same as the amount

flowing in.

E*am#le

E*am#le

+ "f you leave a cu# of hot coffee or a cold

canned drin! on a table, you will find that

after some time both the coffee and the

drin! have the same tem#erature.

+ his is because room tem#erature. he

coffee and the drin! are in thermalequilibrium with room atmos#here.

How liquid in glass thermometer wor!s-

hat did you in this #icture-here is four changes of #hases

/elting

0oiling

SolidificationCondensation

he heat su##lied to a substance during

change of #hase does not cause a changein tem#erature of the substance. hen a

solid melts or a liquid is boiling, heat is

absorbed but the tem#erature remains

constant.

1solid2

1liquid2

Solidification

Heat is released

Melting

Heat is absorbed

Boiling

Heat is absorbedCondensation

Heat is released

1gaseous2

Four main changes of phase

;5


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+ 3atent heat is heat absorbed or the heat

released at constant tem#erature during a

change of #hase

+ S#ecific latent heat is the amount of heat

required to change the #hase of asubstance of ( !g of the substance at a

constant tem#erature.

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