Thermodynamics

Thermodynamics Self Study Part 2 – Phase Change Activity

This picture is a heating curve and the equations used to solve problems associated with this curve.

The above graph shows the heat absorbed by 2,000 g of an unknown substance.

Part 1: Identifying the sections
Give the actual temperature value for #1 – 4

1. What is the freezing point temperature of this substance? [ ]

2. What is the condensation point temperature of this substance? [ ]

3. What is the boiling point temperature of this substance? [ ]

4. What is the melting point temperature of this substance? [ ]

Use either a range of points (a-d = “phase”) or a single point (b = “point”) for #5 – 11.

5. In what section does melting occur? [ ]

6. In what section does boiling occur? [ ]

7. In what section does freezing occur? [ ]

8. In what section does condensation occur? [ ]

9. What area of the graph represents the vapor, or gas, phase? [ ]

10. What area of the graph represents the solid phase? [ ]

11. What area of the graph represents the liquid phase? [ ]

12. Refer to the liquid phase only for the following questions.

A. What is the temperature change during this phase? [ ]

B. From the graph find the amount of heat added (in Joules) during this phase. [ ]

C. Calculate the specific heat of the substance as a liquid. [ ]

13. Refer to the phase change between solid and liquid only for the following questions.

A. The section that refers to this phase change is from point [ ] to point [ ].

B. From the graph find the amount of heat added during this phase. [ ]

C. Calculate the heat of fusion of the substance. [ ]

This picture is a heating curve and the equations used to solve problems associated with this curve.

The above graph shows the heat absorbed by 2,000 g of an unknown substance.

Part 2: Calculations
15. Calculate the specific heat for this substance as a solid. (Show your work)

[enter response]

16. Calculate the heat of vaporization for this substance. (Show your work)

[enter response]

17. Calculate the specific heat for this substance as a gas. (Show your work)

[enter response]

18. How much heat would have to be removed to change the substance from a gas at 180 ºC into a solid at 20 ºC?

[enter response]

19. During which part(s) of the graph is the kinetic energy constant? (label as from point x to point y for each section).

[enter response]

20. During which part(s) of the graph is the potential energy constant? (label as from point x to point y for each section).

[enter response]