Explain what happens to the molecular motion and energy of 1kg of water at 273K when it is changed into ice at same temperature.How is the latent heat of fusion related to the energy exchange that takes place during the change of state?

Asked by DHIRAJ agrawal | 29th Apr, 2013, 08:04: AM

Expert Answer:

Molecular motions are associated with kinetic energy. Faster the molecules move, higher is the kinetic energy. As a liquid solidifies, its molecules comes close together.

When water is converted to ice at the same temperature, there are changes involved in internal potential energy. The molecular motion decreases as heat is released to the surroundings.

Energy involved in the phase chnage = latent heat x Mass

= - 80cal/g x 1000 g

= - 80,000 cal

(-) sign indicates that thermal energy is decreased.

Therfore, when 1 kg water is converted to ice at same temperature, 80,000 cal energy is released (exothermic).

Latent heat of fusion is the amount of heat(energy) which is taken from the surrounding or added to the system in order to change it from solid to liquid at constant temperature.

Answered by  | 18th Jun, 2013, 01:10: PM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.