a doubt on thermodynamics.......in an isothermal process delta(U)=0 right???
but during phase change( water to steam)... its isothermal(constant temperature)....yet almost all of the heat supplied goes on to increase its internal energy...? how?

Question

a doubt on thermodynamics.......in an isothermal process delta(U)=0 right??? 
but during phase change( water to steam)... its isothermal(constant temperature)....yet almost all of the heat supplied goes on to increase its internal energy...? how?

anonymous · Answer

Well.. you may be thinking that the internal energy is total function of temperature.. and so if the temperature remains constant, then even the internal energy should remain a constant.. That is true.. as long as to stick to ONE PHASE. 
But when u are going from one phase to another, the internal energy will change
Internal energy of water at 100 degrees is LESSer than steam at 100 degrees. That additional energy required is precisely what Latent heat concept talks about! (Q = mL)

samgrace · Answer

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