Chemistry: Physical vs Chemical Changes

An ice cube melts into liquid water on a warm table. Is this a physical change or a chemical change? Explain your answer.

A piece of paper is cut into many small pieces with scissors. Is this a physical change or a chemical change? Explain your answer.

A metal bicycle chain is left outside in the rain and begins to rust. Is this a physical change or a chemical change? Explain your answer.

A sugar cube dissolves in a cup of hot tea. Is this a physical change or a chemical change? Explain your answer.

Wood burns in a campfire and produces ash, smoke, heat, and light. Is this a physical change or a chemical change? Explain your answer.

A glass cup breaks into several pieces when it falls. Is this a physical change or a chemical change? Explain your answer.

Vinegar and baking soda are mixed in a cup. Bubbles quickly form and gas escapes. Is this a physical change or a chemical change? Explain your answer.

A student sharpens a pencil, producing small wood shavings and a sharp point. Is this a physical change or a chemical change? Explain your answer.

Milk is left out for several days and develops a sour smell. Is this a physical change or a chemical change? Explain your answer.

A pot of water boils on a stove, and steam rises from the pot. Is this a physical change or a chemical change? Explain your answer.

Classify each change as physical or chemical: tearing aluminum foil, frying an egg, melting butter, and fireworks exploding.

A student observes that two clear liquids are mixed and the container becomes warm. No flame is present. What evidence suggests a chemical change may have occurred?

A crayon is melted and poured into a mold shaped like a star. After cooling, the crayon is solid again. Is this a physical change or a chemical change? Explain your answer.

A science class compares two changes. In Change A, salt water is left in a dish until only salt crystals remain. In Change B, a match burns and leaves black ash. Which change is physical and which is chemical? Explain.

List three common signs that a chemical change may have happened. Then explain why one sign alone is not always enough proof.