Physical vs. Chemical Changes

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.

A chemical change is a change that results in the formation of new chemical substances. Examples include burning, rusting, and cooking.

A physical property is a characteristic of a substance that can be observed or measured without changing its identity. Examples include color, shape, size, and mass.

A chemical property is a characteristic that can only be observed during a chemical reaction. Examples include flammability and reactivity.

Qualitative observations describe characteristics or qualities (e.g., color, taste), while quantitative observations involve measurements and numbers (e.g., height, weight).

Melting ice is a physical change because it changes from solid to liquid without altering its chemical composition.

Signs of a chemical change include color change, temperature change, gas production (bubbles), and the formation of a precipitate.

During a physical change, the arrangement of molecules may change, but the molecules themselves remain the same.

During a chemical change, the bonds between molecules break and new bonds form, resulting in the creation of new substances.

An example of a physical change is water boiling to form steam.