4.3 Specific Latent Heat

There are four main processes in changing of phase, and they are

• Melting

• Boiling

• Condensation

• All the above

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NGSS.MS-PS1-4

Latent heat is

• the heat absorbed or released at a boiling process during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase of 1 kg object

• the heat absorbed or released by an object to increase or decrease its temperature by 1 degree Celcius

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NGSS.MS-PS1-4

NGSS.MS-PS3-4

The heat absorbed by melting a solid is known as

• latent heat of fusion

• latent heat of solid

• latent heat of liquid

• latent heat of vaporisation

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NGSS.MS-PS1-4

the symbol for specific latent heat is

• c

• $l$

• Q

• m

What is the formula to calculate specific latent heat of vaporisation?

• $l=\frac{Q}{m}$

• c = Q/(mΔƟ)

• Q = mcΔƟ

• $Q=ml$

The graph shows the cooling curve of a substance. At which stages the specific latent heat released?

• AB and CD

• BC and DE

• AB and EF

• BC and CD

Tags

NGSS.MS-PS1-4

Calculate the energy absorbed by 30 g of 100 ⁰C water that is turned into 100 ⁰C.

• 67 800 J

• 6 7800 J

• 678 J

• 67.8 J

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

How much energy is required to freeze 150 g of water?
 $\left[l_v=2260000\ J\ kg^{-1};\ l_f=334000\ J\ kg^{-1}\right]$  

• 50 100 cal

• 339 000 J

• 339 000 cal

• 50 100 J

How much energy is required to change 5 kg of ice at 0  $\degree$ C into water at the same temperature? (latent heat of fusion is 3.36 X $10^6$ J/kg )

• 16.1 X $10^6$ J

• 16.8 X $10^6$ J

• 15.1 X $10^6$ cal

• 16.8 X $10^6$ cal

How much energy is required to melt down a 2000 g of mercury?(latent heat of fusion is 1.14 x  $10^4$ J/kg)

• 2.55  x  $10^4$ J

• 2.28 x  $10^4$ J

• 2,280 x  $10^4$ J

• 3.28  x  $10^4$ J