THANK YOU ASHAWIN SIR. I have another question, is like that how melting of ice is isothermal process while its internal energy changes during the transtion of state from ice to water?

Give examples of some physical phenomenon which are example of many thermodynamical process & its cause.

Hi Rahul,

Please do not call us Sir. You can just address by the name.

Coming to your question.

Yes the melting of ice is an isothermal process, because during the process of melting (ie ice being converted to water) the temperature of the mixture of ice and the water that is formed will remain a constant till the entire ice gets melted to water.

For the ice to get melted to water, heat has to be absorbed by the ice to change to water.

Now as per the first law of Thermodynamics,

ΔQ = ΔU + W.

No work is done in this process.

As heat is being absorbed by the ice, the internal energy has to change.

U = nCT ---------(where n is moles of ice, and C is the enthalpy of melting, and temp T which will remain constant during the process of melting)

or ΔU = (Δn)CT --------(it is the number of moles of ice that will change).

One more example of Thermodynamic process, could be the boiling of water. Here a similar thing occurs where water is converted to steam at the boiling point of water.

Hope this helps.

Best Regards,

Ashwin (IIT Madras).