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Question: Answered & Verified by Expert
1.00 kg of liquid water at 100°C undergoes a phase change into steam at 100C at 1.0 atm (take it to be 1.00×105 Pa). The initial volume of the liquid water was 1.00×10-3 m3 which is changed to 2.001 m3 of steam. Find the change in the internal energy of the system.
[Use heat of vaporization 2000 kJ kg-1]
PhysicsThermodynamicsTS EAMCETTS EAMCET 2022 (18 Jul Shift 1)
Options:
  • A 1800kJ
  • B 200kJ
  • C 2000kJ
  • D 80kJ
Solution:
2270 Upvotes Verified Answer
The correct answer is: 1800kJ

According to the first law of thermodynamics,

Q=U+WU=Q-W

The heat given for the phase change of water is Q=mL=2000 kJ.

The change in the volume during phase change is V=2.001-0.001=2 m3.

Work done by the steam will be W=PV=1×105×2=200 kJ.

U=Q-W=2000-200=1800 kJ.

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