Computer Applications
(a) What do you understand by the change of phase of a substance?
(b) Is there any change in temperature during the change of phase?
(c) Does the substance absorb or liberate any heat during the change of phase?
(d) What is the name given to the energy absorbed during a phase change?
Answer
(a) The process of change from one state to another at a constant temperature is called the change of phase.
(b) No, there is no change in temperature during the change of phase.
(c) Yes, the substance absorb or liberates heat during the change of phase. The heat is absorbed during melting and it is liberated during freezing at a constant temperature.
(d) The name given to the energy absorbed during a phase change is latent heat.
Related Questions
The diagram below shows the change of phases of a substance on a temperature-time graph on heating the substances at a constant rate.
(a) What do parts AB, BC, CD and DE represent?
(b) What is the melting point of the substance?
(c) What is the boiling point of the substance?
A substance changes from it's solid state to the liquid state when heat is supplied to it
(a) Name the process.
(b) What name is given to heat absorbed by the substance.
(c) How does the average kinetic energy of molecules of the substance change.
The melting point of naphthalene is 80° C and the room temperature is 25°. A sample of liquid naphthalene at 90° is cooled down to room temperature. Draw a temperature-time graph to represent this cooling. On the graph mark the region which corresponds to the freezing process.
1 kg of ice at 0°C is heated at a constant rate and it's temperature is recorded every 30 s till steam is formed at 100°C. Draw a temperature-time graph to represent the change of phases.