Chemical vs Physical Changes

What is the law of conservation of mass in relation to chemical changes?

• Mass can be created or destroyed in a chemical reaction.

• The total mass of reactants is less than the total mass of products.

• Mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

• The mass of products is always greater than the mass of reactants.

Is cooking an egg a physical or chemical change?

• Physical change.

• Chemical change.

• Neither physical nor chemical change.

• Both physical and chemical change.

Give an example of a physical change.

• Melting ice into water.

• Burning wood to ash.

• Rust forming on iron.

• Baking a cake.

Is dissolving salt in water a physical or chemical change?

• Physical change.

• Chemical change.

• Both physical and chemical change.

• No change at all.

What happens to the chemical composition during a physical change?

• It changes completely; new substances are formed.

• It remains the same; the substance retains its original chemical identity.

• It partially changes; some properties are altered but the substance is still recognizable.

• It becomes unstable and may react with other substances.

What is an example of a reversible physical change?

• Freezing and melting of water.

• Burning of wood.

• Dissolving sugar in water.

• Rusting of iron.

What is an indicator of a physical change?

• Change in color of a substance

• Change in state (solid, liquid, gas) or shape without a change in chemical composition.

• Production of gas during a reaction

• Formation of a precipitate

Can a chemical change be reversed?

• Yes, chemical changes can always be reversed.

• Often, chemical changes are not easily reversible, unlike physical changes.

• Only some chemical changes can be reversed.

• Chemical changes can be reversed with the right conditions.

What is a chemical change?

• A process where one or more substances are transformed into new substances with different properties.

• A physical change that does not alter the chemical composition of a substance.

• A reaction that occurs only in the presence of heat or light.

• A process that involves the mixing of two or more substances without any change in their properties.

Is rusting of iron a physical or chemical change?

• Physical change.

• Chemical change.

• Neither physical nor chemical change.

• Both physical and chemical change.