Physical & Chemical Changes

What is a phase change?

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• A change in the chemical composition of a substance

• A process that occurs only at high temperatures

• A reaction that produces a new substance

What role does energy play in chemical changes?

• Energy is always released during chemical changes.

• Energy has no effect on chemical changes.

• Energy is often absorbed or released during chemical changes, affecting the temperature and state of the substances involved.

• Energy only affects the speed of chemical reactions.

What is deposition?

• A process where a substance changes from a gas to a solid without going through a liquid phase

• A process where a substance changes from a solid to a liquid

• A process where a substance changes from a liquid to a gas

• A process where a substance changes from a gas to a liquid

What is an example of a physical change in the kitchen?

• Boiling water, where water changes from liquid to gas but remains H2O.

• Baking a cake, where ingredients undergo a chemical reaction.

• Toasting bread, which changes its flavor and texture.

• Cutting vegetables, which alters their shape but not their chemical composition.

How can you tell if a chemical change has occurred?

• By observing gas formation, color change, temperature change, or the formation of a precipitate.

• By measuring the pH level of the solution.

• By checking the solubility of the substances involved.

• By observing the physical state of the substances only.

What is a physical change?

• A change that alters the chemical composition of a substance.

• A change that affects one or more physical properties of a substance without altering its chemical composition.

• A change that only occurs at high temperatures.

• A change that results in the formation of a new substance.

What is a precipitate?

• A gas that forms during a chemical reaction.

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

• A liquid that evaporates during a chemical reaction.

• A color change that indicates a chemical reaction has occurred.

What is sublimation?

• Converting a solid into a gas by applying heat

• Converting a liquid into a solid by cooling

• Converting a gas into a liquid by condensation

• Converting a solid into a liquid by melting

What is condensation?

• The process where water vapor becomes liquid

• The process of water evaporating into vapor

• The process of ice melting into water

• The process of water freezing into ice

What is thermal energy?

• Energy expressed in the form of temperature.

• Energy that is stored in chemical bonds.

• Energy associated with the motion of particles in a substance.

• Energy that can be converted into mechanical work.