laten heat fix

8/16/2019 Laten Heat Fix

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LATENT HEAT

Hendri Wijaya

(122014031)

M. Zaky Zen

(122014033)

Dipandu Oleh

Ir. Dewi Ferniani! M".


2/28

H#$"

%'IFI'

H#$"

'$&$'I"

$"#*" H#$"

%OID I+,ID% -$%

"#M$",#


3/28

Wha i/ laen hea

Latent heat is defined as the heat absorbed

or released when a substance changes its

physical state completely at constant

temperature


4/28

2 dieren ype laen hea

1) Latent heat fusion

2) Latent heat of vaporiation


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6/28

!uring melting" the heat absorbed is used tobrea# up the bonds between the particles$

The particles are free from their fi%edpositions and are able to vibrate and moveamong each other $


7/28

Wha i/ laen hea

apriain Latent heat of vaporiation is the heat

absorbed when a li&uid changes into

vapor at constant temperature


8/28

'hen li&uid boils" the heat absorbed is usedto completely brea# the bonds of theparticles and also to do wor# againstatmospheric pressure when the gaseousvapor e%pands into the atmosphere$


9/28

L(*(!

+A,

,-L(! AN!

L(*(!

L(*(!

AN! +A,

. /olecules are

held together

tightly$

. 'hen heated" it

gain energy and

vibrate about

their fi%ed

position at

greater speeds

and amplitudes$

. The li&uid

vapories

completely

into gas$

. The li&uid

temperature

rises$

. /olecules

begin to

moves

faster and

randomly$

. The li&uid starts to boil

. Latent heat of vaporiation is

absorbed the li&uid$

. The solid begin to melt$

. Latent heat of fusion is

absorbed by the solid$

. The molecules are

freed from their fi%ed

positions and are able

to move about$

,-L(!


10/28

Wha i/ /pe5ii5 laen hea

,pecific latent heat" L" of a substance

defined as the amount of heat re&uired to

changed the phase of 1 #g of the

substance at a constant temperature$

(t can be calculated as0

L 6 +78


11/28

where0

latent heat absorbed or released by the

substance

m mass of the substance

The ,$( unit oule per #ilogram 345g91)

The amount of heat re&uired to change thephase of substance depends on the mass

and type of material of the substance


12/28

%u:/an5e

%pe5ii5 laen hea u/in

;'

%pe5ii5 laen hea apriain

;'

k 11?

'hlrr8 A4 9B4 2>4 B2

Mer5ury 11 93@ 2@4 3>A

%ulphur >4 11> 140B 44>

Hydr=en B0 92>@ 44@ 92>3

OCy=en 14 921@ 213 91?3

*ir=en 2> 9210 1@@ 91@B


13/28


u/in

,pecific latent heat of fusion of a substance

defined as the amount of heat re&uired to

change 1 5g of the amount from solid to

li&uid phase at constant temperature


14/28


apriain

,pecific latent heat of vaporiation of a

substance is defined as the amount of

heat re&uired to change 1 5g of the

substance from the li&uid to gaseous

phase without a change in temperature$


15/28

The ,$( unit is oule per #ilogram 345g61)

Heat needed to change one phase to

another phase 0

Q = mL

(f the heat is supplied by immersion

electric heater0

Q = Pt

'here 7 power t time

Pt = mL


16/28

#$M&#%

The specific latent heat of fusion of ice is 889 :::

4;#g$ 'hat is the &uantity of heat re&uired to

melt 1$< #g of ice at :o=$

,olution

Heat re&uired"

ml1$< % 889 :::

54


17/28

A


18/28

E%ample

. =alculate the time ta#en for a


19/28

. 'hat do ( #now@

. Latent heat of fusion of ice l 8$8>%1:


20/28

.'hat do ( #now@

.Latent heat of fusion of ice l 8$8>%1:


21/28

(C level calculation

=alculate the amount of heat re&uired to completely

convert $1? #4;#g;=$ The

specific latent heat of fusion of ice is 88> #4;#g" and the

specific heat of vaporiation of water is 229: #4;#g$

>0=>0

=

0E' 100E


22/28

An e%ample calculation

Heat is ta#en up in three stages

1$ The melting of the ice$

2$ The heating of the water$

8$ The vaporiation of the water$

0E'

0E'

0E' 100E'

100E' 100E'


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24/28

,tage 2

2$ Heat ta#en up heating the water from : D= to the boiling point" 1:: D=

mass of water % specific heat capacity %temperature change :$:< 3#g) % >$1? 3#4$#g61$=61)% 1:: 3D=) 2:$G #4

0E' 100E'


25/28

,tage 8

8$ Heat ta#en up vaporising thewater

mass of water % latent heat of vaporiation:$:< 3#g) % 229: #4$#g61

118 #4

100E' 100E'


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$"#*" H#$"

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$"#*" H#$" I% $%O#D

$"#*" H#$" I% ##$%#D

. L(*(! +A,

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laten heat fix

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