Question

A sample of the substance in the phase diagram is initially at 175∘C and 925 mmHg. The triple point is at 855 mmHg and 145∘C. What phase transition occurs when the pressure is decreased to 760 mmHg at constant temperature?

-liquid to gas
-solid to gas
-solid to liquid
-liquid to solid

Answer 1

The phase transition that occurs when the pressure is decreased to 760 mmHg at a constant temperature of 175°C is from gas to liquid, also known as condensation.

Step-by-step explanation:

The student's question is about what phase transition occurs when the pressure of a substance at a constant temperature is decreased to 760 mmHg from an initial pressure of 925 mmHg. The substance initially at 175°C and 925 mmHg lies in the vapor region according to the description of the phase diagram.

When the pressure decreases to 760 mmHg at constant temperature, the substance crosses from the gas phase to the liquid phase, given that it is above the triple point. This process is known as condensation. Therefore, the phase transition is from a liquid to a gas.