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Coal and Its Fomation

A hydrocarbon...

Question

A hydrocarbon of mass 1.5 kg is just kept in the molten state by a heater of 500 watt. If the heater is switched off, the temp. starts dropping after 4 mins.Calculate the sp. latent heat of fusion of the hydrocarbon?

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Solution

Dear Student

Heat energy lost in 4 min can be given as
$Q = \frac{P}{t} = \frac{500}{4 \times 60} = 2.083 J T h i s h e a t e n e r g y k e e p s 1.5 k g h y d r o c a r b o n i n m o l t e n s t a t e . S o Q = m L L = \frac{Q}{m} = \frac{2.083 J}{1.5} = 1.39 J / k g$

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