Phase Change Lesson

A car mechanic had a sealed bucket containing a substance in the gas phase. She left the bucket outside over the weekend. When she returned, the substance had changed phase, and the substance was in the liquid phase. What happened to the molecules of this substance?

• Before the mechanic left, the molecules were moving away from each other. When she returned, they were moving around each other.

• Before the mechanic left, the molecules were moving around each other. When she returned, they were moving in place.

• Before the mechanic left, the molecules were moving around each other. When she returned, they were moving away from each other.

• Before the mechanic left, the molecules were moving in place. When she returned, they were moving around each other.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

A chef finds a sealed container consisting of an ingredient that goes into his restaurant’s secret sauce. The ingredient’s molecules are moving in place. What will happen if the chef causes the ingredient to change phase by transferring energy into it?

After the phase change, the ingredient’s molecules will move . . .

• faster, and the ingredient will be a solid.

• faster, and the ingredient will be a liquid.

• slower, and the ingredient will be a solid.

• slower, and the ingredient will be a liquid.

Tags

NGSS.MS-PS1-4

The image above shows information about two different substances in sealed containers. A scientist transfers the same amount of energy into both substances. One substance changes phase, but the other does not. Which chemical changed phase, and why did it change?

• Substance A changed phase because its molecules were able to move fast enough to overcome the attraction between them. It is now a gas.

• Substance A changed phase because the weak attraction between its molecules allowed them move faster. It is now a gas.

• Substance B changed phase because the molecules were able to move fast enough to overcome the attraction between them. It is now a gas.

• Substance B changed phase because the strong attraction between molecules made their movement slower. It is now a solid.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

A student left a jar of water outside his home. Water can be a solid, liquid, or gas. When he put the jar outside, the water was liquid. Twelve hours later, the water had changed phase and was a gas. What happened to the water molecules?

• When the student left the jar outside, the molecules were moving around each other. Later, the molecules were moving in place.

• When the student left the jar outside, the molecules were moving away from each other. Later, the molecules were moving around each other.

• When the student left the jar outside, the molecules were moving in place. Later, the molecules were moving around each other.

• When the student left the jar outside, the molecules were moving around each other. Later, the molecules were moving away from each other.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Scientists have a container of water. Water can be a solid, liquid, or gas. At first, the water molecules in the container were moving around each other. Later, the water molecules were moving in place. What change did the scientists observe?

• At first, the water was a gas. After, it was a liquid.

• At first, the water was a solid. After, it was a liquid.

• At first, the water was a liquid. After, it was a gas.

• At first, the water was a liquid. After, it was a solid.

Tags

NGSS.MS-PS1-4

An Earth scientist brought an unknown substance from underground back to her lab. The substance was in the gas phase and was put into a sealed tank as shown above. She slowed down the molecules inside the tank and the substance changed phase. How did she do this, and how did it affect the molecules? She transferred energy . . .

• into the substance, and the molecules moved around each other.

• into the substance, and the molecules moved away from each other.

• out of the substance, and the molecules moved around each other.

• out of the substance, and the molecules moved in place

Tags

NGSS.MS-PS1-4

Two different cars, the Model S and Model T, use different substances in their engines. The image above shows the two substances. At room temperature, both substances are liquids. A car mechanic transferred the same amount of energy out of the two containers, but only one substance changed phase. Which car’s substance changed phase, and how did it change?

• The Model T’s substance changed phase because the attraction of the molecules was able to overcome their slower movement. Its molecules now move in place.

• The Model T’s substance changed phase because the strong attraction between the molecules made their movement slower. Its molecules now move in place.

• The Model S’s substance changed phase because the weak attraction between the molecules allowed them to move faster. Its molecules now move around each other.

• The Model S’s substance changed phase because the attraction was able to overcome the slower molecules. Its molecules now move away from each other.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Workers find two substances. One is a toxic chemical. The other is a safe chemical. Both chemicals are liquids at room temperature. As a test, the workers transfer the same amount of energy out of the two containers and find that only the toxic chemical changes phase. How is the toxic chemical different from the safe chemical?

• weaker attraction between its molecules than the safe chemical. Its molecules now move in place.

• weaker attraction between its molecules than the safe chemical. Its molecules now move around each other.

• stronger attraction between its molecules than the safe chemical. Its molecules now move away from each other.

• stronger attraction between its molecules than the safe chemical. Its molecules now move in place.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Detectives find two substances at a crime scene. One is a poison, and the other is a cleaning chemical. At room temperature, both substances are liquids. To test the substances, the detectives transfer the same amount of energy into both substances, but only the cleaning chemical changes phase. How is the cleaning chemical different from the poison?

• weaker attraction between its molecules than the poison. Its molecules now move in place.

• weaker attraction between its molecules than the poison. Its molecules now move away from each other.

• stronger attraction between its molecules than the poison. Its molecules now move away from each other.

• stronger attraction between its molecules than the poison. Its molecules now move around each other.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What is the key concept related to phase change at the molecular scale?

• A change in state

• A change in freedom of movement

• A change in temperature

• A change in color

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4