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 47. °c and 1.3 atm. what will be the state of the sample? suppose the temperature is held constant at 47. °c but the pressure is decreased by 0.9 atm. what will happen to the sample? suppose, on the other hand, the pressure is held constant at 1.3 atm but the temperature is decreased by 153. °c. what will happen to the sample?

Explanation:

Step1: Convert temperature to Kelvin

First, convert $47^{\circ}C$ to Kelvin. The conversion formula is $K = ^{\circ}C+ 273$. So, $T = 47 + 273=320K$, and the pressure $P = 1.3atm$. Locate the point $(320K, 1.3atm)$ on the phase - diagram. We can see that the sample is in the liquid state.

Step2: Calculate new pressure

The new pressure when the pressure is decreased by $0.9atm$ from $1.3atm$ is $P_{new}=1.3 - 0.9 = 0.4atm$ at a constant temperature of $320K$. Locate the point $(320K,0.4atm)$ on the phase - diagram. The sample will be in the gas state, so it will vaporize (change from liquid to gas).

Step3: Calculate new temperature

The new temperature when the temperature is decreased by $153^{\circ}C$ from $47^{\circ}C$ is $T_{new}=47-153=- 106^{\circ}C$. Convert this to Kelvin: $T_{new}=-106 + 273 = 167K$ at a constant pressure of $1.3atm$. Locate the point $(167K,1.3atm)$ on the phase - diagram. The sample will be in the solid state, so it will freeze (change from liquid to solid).

Answer:

1. Liquid
2. It will vaporize
3. It will freeze