Phase Changes on a Graph

Phase Change Gizmo Review

Multiple Choice

1. Match the description to the correct phase of matter. *

Molecules are held loosely but free to flow, no fixed shape, fixed volume

• Solid

• Liquid

• Gas

Multiple Choice

Molecules are held tightly and connected (rigid), fixed shape, fixed volume.

• Solid

• Liquid

• Gas

Multiple Choice

Molecules are free to move, no fixed shape, no fixed volume.

• Solid

• Liquid

• Gas

Multiple Choice

2. The graph represents the heating of water in a pot. At 150 seconds, the water has just begun to boil. If the heat is left on, what will happen to the temperature and volume of water in the pot? (All temperatures in °C.) *

• The temperature will rise, and the water volume will decrease.

• The temperature will rise, and the water volume will remain the same.

• The temperature will remain the same, and the water volume will decrease

• The temperature will remain the same, and the water volume will remain the same.

Multiple Choice

3. Which of the following statements is most accurate? *

• When liquid water is heated, the molecules move slower.

• When liquid water is heated, the molecules move faster.

• When liquid water is heated, the molecules move at the same speed.

Multiple Choice

4. In a pressure cooker, a lid is screwed tightly onto a pot so that the air pressure in the pot is increased. What effect, if any, will this have on the boiling point of water in the pot? *

• The boiling point will be unaffected.

• The boiling point will be raised.

• The boiling point will be lowered.

• None of the above.

Open Ended

5. Why does pasta take longer to cook in the mountains? *

Multiple Choice

6. Which of the following descriptions explains the process of water freezing? *

• Water molecules speed up until they escape into a different phase

• Water molecules slow down until they escape into a different phase.

• Water molecules slow down until they begin to bond together.

• Water molecules speed up until they begin to bond together.

Multiple Choice

7. How many phase changes are occurring in the graph below? *

• 1

• 2

• 3

• 4

Multiple Choice

8. What altitude is the following data representing? *

• Above Sea Level

• At Sea Level

• Below Sea Level

Open Ended

9. Give an explanation for the answer you chose for the question above (# 8). *

Open Ended

10. What is occurring between 475 seconds and 625 seconds? Explain how you know. *

Open Ended

11. Restate-Answer-Prove: Based on what we have observed in this phase change gizmo, explain why phase changes occur? *

Key Concepts from Activity A

• During a phase change the temperature will remain constant.

• A phase change on a graph will be a straight horizontal line

• Melting Point of water at sea level is 0 degrees Celsius.

• Freezing Point of water at sea level is 0 degrees Celsius.

• Boiling Point of water at sea level is 100 degrees Celsius.

Key Concepts from Activity B

• Phase Changes occur due to molecular motion.

• As temperature increases molecules increase in speed.

• As temperature decreases molecules decrease in speed.

Key Concepts from Activity C

• Altitude affects the boiling point of water.

• Higher altitude = low air pressure = lower boiling point

• Lower altitude = higher air pressure = higher boiling point