This chapter explores the concept of changes that occur in our surroundings and categorizes them into physical changes and chemical changes.
Changes can be broadly classified into two types: physical changes and chemical changes.
Physical changes are changes that alter the physical properties of a substance without forming a new substance. Examples include changes in state (solid, liquid, gas), changes in shape or size, changes in texture, etc.
Examples of physical changes - melting of ice, freezing of water, evaporation of liquid, condensation of vapor, dissolving sugar in water, etc.
Chemical changes involve the formation of new substances with different properties. Signs of chemical changes include the release of heat or light, formation of a gas, change in color, change in smell, etc.
Examples of chemical changes - burning of paper, rusting of iron, cooking of food, etc.
Reversible changes can be undone, while irreversible changes cannot be reversed.
Conservation of mass states that the total mass of substances involved in a physical or chemical change remains constant.