Physical/Chemical Changes

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

• A physical change alters the chemical composition of a substance, while a chemical change does not.

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

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

• A physical change and a chemical change are essentially the same.

What are indicators of a chemical change?

• Color change, temperature change, gas production, and formation of a precipitate.

• Change in mass, change in volume, change in density, and change in shape.

• Color change, melting, freezing, and boiling.

• Change in state, change in pressure, change in temperature, and change in color.

Is dissolving sugar in water a physical or chemical change?

• A physical change because the sugar can be recovered by evaporating the water.

• A chemical change because it alters the molecular structure of sugar.

• A physical change because it creates a new substance.

• A chemical change because it cannot be reversed.

Give an example of a chemical change.

• The reaction of vinegar and baking soda, which produces carbon dioxide gas.

• Melting of ice into water.

• Dissolving sugar in water.

• Boiling water to produce steam.

What is a precipitate?

• A solid that forms and settles out of a liquid mixture during a chemical reaction.

• A gas that is released during a chemical reaction.

• A liquid that evaporates during a chemical reaction.

• A color change that occurs during a chemical reaction.

What is rusting an example of?

• A physical change

• A chemical change

• A biological change

• A mechanical change

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

• The law states that mass can be created or destroyed in a chemical reaction.

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

• The law states that mass is neither created nor destroyed in a chemical reaction; the total mass of the reactants equals the total mass of the products.

• The law states that mass is only conserved in physical changes, not in chemical reactions.

What role does energy play in chemical changes?

• Energy is always released during a chemical change.

• Energy has no effect on chemical changes.

• Energy is often absorbed or released during a chemical change, which can cause temperature changes or the production of light.

• Energy only affects physical changes, not chemical changes.

Give an example of a physical change.

• Ice melting into water.

• Burning wood to ash.

• Rust forming on iron.

• Baking a cake.

What is an example of a reversible physical change?

• Freezing water to make ice.

• Burning wood to ash.

• Dissolving sugar in water.

• Breaking a glass bottle.