Below is a phase diagram for compound X. What is the normal boiling point of X is most likely to be?
A) 0° C
B) 73° C
C) 15° C
D) 47° C
E) 18° C

Question

Below is a phase diagram for compound X. What is the normal boiling point of X is most likely to be? 
A) 0° C 
B) 73° C 
C) 15° C 
D) 47° C 
E) 18° C

Quizplus · Accepted Answer

The normal boiling point occurs at the point where the vapor pressure curve intersects with the atmospheric pressure line. In this phase diagram, that occurs at approximately 47°C, which is the best choice. A is incorrect because the boiling point cannot be at 0°C since the solid-liquid line has a positive slope. B is incorrect because the normal boiling point occurs at 1 atm, not 5 atm. C is incorrect because the boiling point would be below room temperature which is highly unlikely. E is incorrect because the normal boiling point should be at a higher temperature than the triple point.

Below Is a Phase Diagram for Compound X