Phase Change Critical Juncture

Front

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?

Back

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

Front

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 . . .

Back

faster, and the ingredient will be a liquid.

Front

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?

Back

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

Front

What change did Cesar and Ming observe to the water?

Back

At first, the water was a solid. Later, it was a liquid.

Front

How would a phase change occur for a solid substance under extreme conditions, and how would the molecules be affected?

Back

Energy would be transferred into the substance, and its molecules would move around each other.

Front

Which chemical changed phase, and why did it change?

Back

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

Front

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?

Back

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

Front

Refrigerators are able to transfer energy out of a substance. At first, the substance is a gas. The refrigerator changes the phase of the substance by transferring energy out of it. How does this change affect the substance’s molecules? After the phase change, the molecules move . . .

Back

slower, and they move around each other.

Front

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?

Back

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

Front

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?

Back

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