Phase Change Quiz

Particles in each state of matter behave differently because they have different amounts of thermal energy. In a solid, the particles are held together tightly, and they do not move around freely. Because the particles stay in about the same place, a solid generally keeps a certain shape. Even though particles in a solid cannot move past one another, they are not completely still. The particles are constantly vibrating, or moving back and forth, in place. Select all the true statements.

• Particles in a solid are completely still.

• Particles in a solid have thermal energy.

• Particles in a solid are packed tightly.

What happens when you heat a solid? Heating a substance increases its thermal energy. When the particles in a solid have more thermal energy, they vibrate more quickly, and the temperature of the substance goes up. Once the substance reaches a certain temperature, called its melting point, the substance can begin to change state. As more thermal energy is added to the substance, its particles gain enough thermal energy to move around more freely. The particles remain close together, but they are able to slide past one another. When all of the particles have broken out of their fixed positions, the substance has changed state. Which of the following happen during this change of state? Select all that apply.

• A. The substance melts and becomes a liquid.

• B. The number of particles in the substance increases.

• C. The particles in the substance move far apart.

The particles in both solids and liquids are arranged close together. But when a substance is a liquid, its particles have more thermal energy than they would if the substance were a solid. Particles in a liquid can slide past one another. Because of how these particles move, a liquid is able to flow and take the shape of its container.

• Liquid

• Solid and Liquid

• Solid

• Liquid

• Solid and Liquid

• Solid

What happens when you heat a liquid? The particles begin to slide past one another more and more quickly, and the temperature of the substance goes up. When the temperature reaches the substance's boiling point, the particles have enough thermal energy to begin moving far apart and escaping the liquid.

• A. The particles gain thermal energy.

• B. The substance vaporizes and becomes a gas.

• C. The mass of each particle increases.

Place each statement into the correct column:

• Both liquids and gases

• Liquids

• Liquids

• Both liquids and gases

• Gases

• Gases

Based on the passage above, describe how particles in a substance behave as thermal energy decreases.

• As thermal energy decreases, the particles in a gas move more slowly, condense to form a liquid, and then freeze to form a solid. In a solid, the particles vibrate in place more slowly.

• As thermal energy decreases, the particles in a substance move faster and spread farther apart, eventually turning into a gas.

• As thermal energy decreases, the particles in a solid begin to move rapidly and break apart into a liquid, then a gas.

• As thermal energy decreases, the particles in a substance stop moving completely and disappear.

What is true about the particles in a substance? Select all that apply.

• The way particles move changes when the substance's thermal energy changes.

• Heating a substance can cause the substance to change state.

• Particles in all states of matter are constantly moving.

• Particles in all states of matter are arranged close together.