Question
What is the Internal energy in the process of vapourisation?
✓
Answer
During vapourisation, volume increases. So work done $=P\left(V_f-V_i\right)$ and temperature does not change. So, $d Q=m L_v$
$\therefore$ from first law of thermodynamics, $d U=d Q-D W=m L_v-P\left(V_f-V_i\right)$.
$\therefore$ from first law of thermodynamics, $d U=d Q-D W=m L_v-P\left(V_f-V_i\right)$.
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