Question

Experiment:Take a beaker of water, keep it on the burner .Note the readings of
thermometer for every 2 minutes.
• Did you see any rise or fall in the level of the surface of the water, in
the beaker? Why?
• Does the temperature rise continuously?
• When does the rise in temperature of water stop?

Answer 1

Experiment : Take a beaker of water, keep it on the burner .Note the readings of thermometer for every 2 minutes.

• Did you see any rise or fall in the level of the surface of the water, in the beaker? Why?

There was a fall in the level of surface of the water, as some water was evaporated. Evaporation is a phenomenon occurring at all temperatures.

• Does the temperature rise continuously?

The temperature rises steadily till it reaches a certain temperature, after which there is no rise in temperature.

• When does the rise in temperature of water stop?

The rise in temperature of the water stops when the water attains its Boiling point. At the temperature of Boiling point, All the heat given to water is used increase the intermolecular forces and to change the state of water from liquid to gas

Answer 2

Experiment :

Take a beaker of water, keep it on the burner .

Note down the readings of the thermometer for every 2 minutes.

We observe that

• Initially there will be drop / fall in the level of  water at the top surface as water evaporates and we know that evaporation occurs at all temperatures.

•  Then as the heat energy is supplied to water there will steady rise in temperature of the thermometer .

• Then mercury in thermometer will rise till it reaches 100°c  .

• At 100°c , mercury level in the thermometer will be constant, because the heat supplied is used as latent heat of vaporization to convert the liquid into gas