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 changes in state (like melting or freezing), shape, or size.

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 molecular structure of the original substance.

Front

Give an example of a physical change.

Back

Examples of physical changes include crumpling paper, melting ice, and dissolving sugar in water.

Front

Give an example of a chemical change.

Back

Examples of chemical changes include rusting of iron, burning wood, and souring of milk.

Front

What is a sign that a chemical reaction has occurred?

Back

Signs of a chemical reaction include the formation of a gas, change in color, temperature change, and the formation of a precipitate.

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

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

Back

During a physical change, the properties of the substances may change (like shape or state), but the chemical identity remains the same.

Front

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

Back

During a chemical change, the properties of the substances change, and new substances with different properties are formed.

Front

What is a mixture?

Back

A mixture is a combination of two or more substances where each retains its own properties and can be separated by physical means.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change does not alter the chemical composition of a substance, while a chemical change results in the formation of new substances.