1 g of a liquid is converted to vapour at 3 × 10 5 Pa pressure. If 10 % of the heat supplied is used for increasing the volume by 1600 cm 3 during this phase change, then the increase in internal ener

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1 g of a liquid is converted to vapour at 3 × 10 5 Pa pressure. If 10 % of the heat supplied is used for increasing the volume by 1600 cm 3 during this phase change, then the increase in internal energy in the process will be :

TestHub · Accepted Answer

As pressure against which expansion is happening is constant, work done can be written as $= P Δ V$

$= (3 \times 10^{5}) \times (1600 \times 10^{- 6})$

$= 480 J$
As only $10 %$ of heat is used in work done.
Hence $Δ Q = \frac{W}{0.1} = 4800 J$
The rest goes in increase in internal energy, which is $90 %$ of heat.
Change in internal energy $= 0.9 \times 4800 = 4320 J$

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