Effect of Heating

Introduction

We heat raw food to soften it. We freeze water into ice by cooling it in refrigerator. When we boil water in a kettle we observe the steam oozing from the mouth of the kettle. When the cork is difficult to remove, we slightly heat the mouth of the bottle, so that the cork comes out easily. Through daily experience we know that heating can produce -

• Change in temperature

• Expansion of matter

• Change of state

• Change in electrical properties

• Change in chemical properties

Change in Temperature

We have already observed that when a substance is heated, the very first effect we observe is that its temperature rises. Similarly when a substance is cooled (i.e. heat energy is removed from the substance) the temperature of a substance decreases.