Question

when water is heated to higher temperature, does its temperature change continuously over time? Explain

Answer 1

Say, water is being boiled in a metal container

The water molecules closest to the metal container will attain phase change quite soon since the local temperature exceeds boiling temperature of water. However these tiny bubbles of water form but are not able to reach the surface as the rest of the water is quite cold and it absorbs all the heat before the has a chance to escape to the surface. With continued heating, due to heat transfer the water in the container is hot enough and the steam formed in the boundary of container and water starts joining with other steam bubbles and attempts to escape the liquid by rising to the top due to lower density of steam. After more heating the liquid reaches a temperature of boiling point and accelerated bubble formation And escape of steam occurs. Heating beyond this point causes a layer of steam to build up between the metal and water and this steam acts like a blanket and inhibits the transfer of energy to the water (steam is a poor conductor of heat, just like most gases are poor conductors of heat compared to their liquid form). Due to this, the rate of boiling slows down. But as the heating of water is continues, the steam blanket gets superheated and is no longer a very good insulator, hence the rate of boiling is accelerated again until all of the water is boiled away.

Answer 2

Hey Mate Here's your answer ,
hope this will help you
When the water is heated to higher temperature it's temperature remains unchanged until it is converted into vapour and the extra heat is been absorbed by the water to overcome atmospheric pressure and the heat absorbed is called latent heat of vaporization