Computer Applications
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?
Answer
(a) The different parts represent the following:
- Part AB — It shows the rise in temperature of solid from 0°C to t1°C.
- Part BC — It shows melting at temperature t1°C.
- Part CD — It shows the rise in temperature of liquid from t1°C to t3°C.
- Part DE — It shows boiling at temperature t3°C
(b) The melting point of the substance is t1° C.
(c) The boiling point of the substance is t3° C.
Related Questions
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.
(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?
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