Changes that matter undergo are generally classified into physical and chemical changes. Chemists learn a lot about the nature of matter by studying the changes that matter can undergo.
Changes that matter undergo are generally classified into physical and chemical changes. Chemists learn a lot about the nature of matter by studying the changes that matter can undergo.
These are changes that do not involve the formation of new products. Here, no bonds are broken or formed. Starting materials are the same as ending materials. Physical changes involve the movement of particles within a substance but not a change of these particles. Physical changes are generally reversible but not in all cases. For example, cracking an egg is a physical change that is irreversible. Examples of physical changes include:
These are changes that involve the formation of new products. It results when a substance combines with another to form a new substance (synthesis or either decomposes to form more substances). The oxidation reaction is a chemical change example that causes a chemical reaction.
Generally, Chemical changes are irreversible. However, chemical reactions under certain conditions can be reversible. Examples of chemical reactions include:
| Physical changes | Chemical changes |
|---|---|
| Involves a new substance forming with different properties. | No new substance is formed; only the state or appearance changes. |
| It is generally reversible. | It is generally irreversible. |
| It involves the movement of subatomic particles. No change in molecular composition. | it involves changes in the molecular composition. |
| Generally, physical changes do not involve the production of energy. | Chemical changes usually involve the production of energy (which can be in the form of heat, light, sound, etc.) |
| Physical changes are usually temporary. | Chemical changes are usually permanent. |
| Physical changes affects only the physical makeup of a substance i.e shape. | Chemical changes affects the composition, physical and chemical properties of a substance. |
| There is generally no change in mass of substances involved. | It generally involves change in the mass of substances involved. |
| A physical change involves very little to no absorption of energy. | During a chemical reaction, absorption and evolution of energy take place. |