The phase diagram of a substance is shown below.
-The approximate normal boiling point of this substance is
A)180 K.
B)190 K.
C)300 K.
D)430 K.

Question

The phase diagram of a substance is shown below. 
-The approximate normal boiling point of this substance is
A)180 K. 
B)190 K. 
C)300 K. 
D)430 K.

Quizplus · Accepted Answer

The normal boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. From the phase diagram, we can see that the atmospheric pressure is approximately 1 atm at around 300 K. Therefore, the approximate normal boiling point of this substance is 300 K. Option A and B are too low, and Option D is too high for the normal boiling point of this substance according to the given phase diagram.

The Phase Diagram of a Substance Is Shown Below