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PCAT Chemical Processes – Solid to Gas

  • by Sam
  • Dec 18, 2017
  • PCAT Question of the Day

The following is a phase diagram showing the transition from solid to gas as heat is added to a substance:

Which of the following correctly indicates the relationship between the regions of the graph and the corresponding phases:

A) 1: solid, 2: phase change from solid to liquid, 5: gas

B) 2: solid, 3: phase change from solid to liquid, 4: liquid

C) 1: phase change from solid to liquid, 4: gas

D) 1: solid, 2: phase change from liquid to gas, 3: liquid

Click for Explanation

The diagram shows the relationship between heat added to a substance and its temperature. It shows that during phase changes there is no change in the temperature. The regions noted are:

1: solid

2: phase change from solid to liquid (melting / fusion)

3: liquid

4: phase change from liquid to gas (boiling / vaporization)

5: gas

Only choice (A) correctly indicates these regions.

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