Chemical and physical changes

Question 1

What is a chemical change?

Answer 1

A chemical change produces a new substance, involves the breaking and forming of chemical bonds, and is typically irreversible (but not always).

Question 2

What is a physical change?

Answer 2

A physical change does not produce a new substance, no chemical bonds are broken or formed, and is often reversible (but not always).

Question 3

What are the signs of a chemical change?

Answer 3

• Colour change
• Temperature change (exothermic or endothermic)
• Gas production (bubbles or fizzing)
• Formation of a precipitate
• Light or sound emission

Question 4

What are the signs of a physical change?

Answer 4

• Change in state (solid → liquid → gas, etc.)
• Change in shape or size (stretching, cutting, etc.)
• Dissolving (solute mixing with solvent without forming a new substance)