4.3 SPECIFIC LATENT HEAT

3. How steam is used to cook food?

• Water has large specific latent
heat of vaporisation

• When the steam condenses on
the fish,

• the specific latent heat is
released directly to the fish.

• This enable the fish to be
cooked faster

4. Explain why our body feel cool after
sweating.

• The sweats on the body
evaporates.

• It absorbs specific latent heat of
vaporisation from the body.

• As a result, the body is cooled
by the removal of the heat

5. Why the burn due to steam is more
serious than the burn due to hot
water only?

• Water has large specific latent heat of
vaporisation.

• When steam condenses on the skin, large
amount of heat is released to the skin.

• Can cause serious injuries.



Name the cooling agent used. Freon

A refrigerator uses the cooling effect
from …ev…ap…or…at…ion During circulation of
the cooling agent, heat is a…b…so…rb…ed….
from inside the refrigerator and
r…el…ea…se…d. outside.

1. Compressor compresses cooling agent (gas) to
increase pressure and its temperature.

2. Condenser
In the condenser, cooling agent (gas)
releases latent heat during condensation.

3. Expansion valve
Cooling agent (liquid) flows
through expansion valve. This
valve has tiny hole which allows
liquid at high pressure is ejected
into the evaporator tube which is
at lower pressure. Liquid changes
to gas.

4. Freezer
In the evaporator (freezer), cooling agent (in
liquid) evaporates and absorbs latent heat
from inside the refrigerator.

5. Cooling agent / Freon
Cooling agent in gas flows out from
evaporator to the compressor.



THE END