Every substance requires some energy to change its form. Without energy it can not transform from solid into liquid, from liquid into vapor or from vapor into liquid. Sometimes energy is derived in the form of heat from the atmosphere; otherwise it has to be provided by heating. E.g. one gram water at 0° Celsius freezing point is in the solid form of ice. In order to heat up to boiling point it has to be given 100 calories heat. Cube of an ice already melted into water starts agitating (boiling) at the stage. Now, if one wants to convert that boiling water into steam, heat required for that purpose will be about 540 calories! A question immediately arises: How did the figure of calories rise so high?
- Why does heat make paper curl up?
- Which liquid substance boils when it is cold?
- Why does water gurgle when it’s flowing out from a bottle?
- How does gargling with salt water help to cure sore throat?
- Why sugar dissolves faster in hot water than in cold water?
- Why hot water appears milky white when drawn from the faucet?