Question

study the following phase diagram of substance x. use this diagram to answer the following questions. suppose a small sample of pure x is held at 16. °c and 0.8 atm. what will be the state of the sample? suppose the temperature is held constant at 16. °c but the pressure is decreased by 0.5 atm. what will happen to the sample? suppose, on the other hand, the pressure is held constant at 0.8 atm but the temperature is decreased by 88. °c. what will happen to the sample?

Explanation:

Step1: Convert temperature to Kelvin

$T = 16^{\circ}C+ 273 = 289\ K$, $P = 0.8\ atm$. Locate this point on the phase - diagram. The point lies in the solid region.

Step2: Calculate new pressure

The new pressure $P_{new}=0.8 - 0.5=0.3\ atm$, temperature $T = 289\ K$. Locate this point on the phase - diagram. It lies in the gas region, so the sample will sublime (change directly from solid to gas).

Step3: Calculate new temperature

The new temperature $T_{new}=16 - 88=- 72^{\circ}C = - 72+273 = 201\ K$, pressure $P = 0.8\ atm$. Locate this point on the phase - diagram. It is still in the solid region, so no phase change occurs.

Answer:

1. Solid
2. Sublime (change directly from solid to gas)
3. No phase change occurs