Physical changes do not produce new substances, but chemical changes do produce new substances. A physical change is concerned with states of matter. Melting, vaporization, freezing, sublimation and condensation are physical changes. Melting an ice cube is a physical change because the substance remains as water. Most physical changes are reversible. Crushing a can, boiling water, breaking glass, chopping wood, mixing sand and water, and shredding paper are physical changes.Continue Reading
Chemical changes occur on the molecular level. The change produces a new substance. Chemical changes include combustion, synthesis, oxidation, neutralization and decomposition. For example, iron rusting is an instance of a chemical change. Food metabolism, burning wood, mixing and acid with a base, baking a cake and using a chemical battery are also examples of chemical changes.
A chemical change can be determined by evaluating if a reaction has occurred. A chemical reaction may have occurred if a change in light, heat, color, gas production, odor or sound is produced. If a precipitate develops, then a chemical change has occurred. An odor is a sign of a chemical change because it is evidence that decomposition is occurring. For example, a rotten egg produces an odor as it transforms into a new substance.Learn more about Chemistry
Physical properties are characteristics of matter that can be observed without making any changes to the chemical composition of that given matter. In academic contexts, physical properties are often contrasted with chemical properties.Full Answer >
Harper College explains that forming a precipitate, color changes, gas formation and temperature change are signs of a chemical change. The University of California, Davis adds that the presence of odor also indicates a chemical change. There are only five indicators of a chemical change.Full Answer >
The term "chemical reaction" refers to any process that changes a set of chemical substances to another. That is, the substances that are put into a chemical reaction are different, on a molecular level, from those that result.Full Answer >
Enzymes are naturally occurring proteins that are found in the bodies of certain living things, including humans and other animals, and that cause chemical changes such as breaking down food in the stomach. Within the human body, enzymes can be found in bodily fluids, such as blood, saliva, the gastric juices or the stomach and fluids in the intestines. In general, enzymes serve as catalysts for biological functions, including natural, involuntary bodily functions, such as blood clotting.Full Answer >