Final answer:
A physical change involves a change in the state or properties of matter without changing its chemical composition. In contrast, a chemical change results in the formation of new substances with different chemical properties. Indications such as changes in state or the formation of a precipitate can help distinguish between physical and chemical changes.
Step-by-step explanation:
A physical change is a change in the state or properties of matter without any accompanying change in the chemical composition of the substances. Examples of physical changes include changes in state, such as the boiling of water to form steam, or changes in shape or size, such as cutting a piece of paper. In contrast, a chemical change is a change that results in the formation of new substances with different chemical properties. Examples of chemical changes include the rusting of iron, the burning of wood, or the digestion of food in the body.
To distinguish between physical and chemical changes, we can look for certain indications. If a substance changes its state of matter without any change in its chemical composition, then it is a physical change. For example, when water boils and becomes steam, it is still made up of the same water molecules, so it is a physical change. On the other hand, if a substance undergoes a chemical change, it will not retain its original properties because new substances with different properties are formed. For instance, when a precipitate is formed when two substances are mixed, it indicates a chemical change because the precipitate is a new substance.