define latent heat of fusion and illustrate with a suitable examples
Answers
The amount of heat energy released or absorbed when a solid changing to liquid at atmospheric pressure at its melting point is known as the latent heat of fusion. ... The latent heat of fusion of water is 79.72 cal/gram (or) 334.0 kJ/Kg.
Latent heat of fusion :-The energy per kilogram required to cause a substance to change state from solid to liquid at its melting point.
Word Fusion means Melting in this sentence.
In simple words it is latent heat of fusion is the amount of heat energy required to change 1Kg of solid to liquid.
Example:-
1) Heat pipes-
One solution is the heat pipe. As its name suggests, it transfers heat from high temperature regions to lower temperature regions where there is more space for heat sinks or cooling fans.
2)How much heat is needed to transform 500g of ice at -20 oC into water at 50 oC ? (cice = cwater / 2) .
This is done in 3 stages, each one of them taking a different amount of heat (Q):
Q1 = heating up the ice from -20 oC to 0 oC
Q2 = melting the ice
Q3 = heating up the water (molten ice) from 0 oC to 50 oC.
Q1 = c m Δt = 2093*0.5*20 = 20930 J
Q2 = Lf m = 3.33 x 105 *0.5 = 170000 J
Q3 = c m Δt = 4186*0.5*50= 104650 J
The total heat taken is Q1+Q2+Q3 = 295580 J = 295.58 kJ
Interesting to obeserve that melting the ice is the step that takes the most energy (heat).
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I hope it is helpful...