Physical and Chemical Changes

Front

What is a physical change?

Back

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.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. It involves a chemical reaction and changes the chemical composition of the substance. Examples include rusting, burning, and digestion.

Front

Give an example of a physical change.

Back

An example of a physical change is ice melting into water.

Front

Give an example of a chemical change.

Back

An example of a chemical change is the burning of wood, which produces ash and smoke.

Front

What are indicators of a chemical change?

Back

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

Front

What happens to the mass of substances during a physical change?

Back

The mass of substances remains the same during a physical change because no new substances are formed.

Front

What happens to the mass of substances during a chemical change?

Back

The mass of substances is conserved during a chemical change; however, it may appear to change due to the formation of new substances.

Front

Is dissolving sugar in water a physical or chemical change?

Back

Dissolving sugar in water is a physical change because the sugar can be recovered by evaporating the water.

Front

Is burning paper a physical or chemical change?

Back

Burning paper is a chemical change because it produces new substances such as ash and gases.

Front

What is the difference between a reversible and irreversible change?

Back

A reversible change can be undone (like melting ice), while an irreversible change cannot be undone (like baking a cake).