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 - 123. °c and 20.9 atm. what will be the state of the sample? suppose the temperature is held constant at - 123. °c but the pressure is decreased by 16.9 atm. what will happen to the sample? suppose, on the other hand, the pressure is held constant at 20.9 atm but the temperature is decreased by 116. °c. what will happen to the sample?

Explanation:

Step1: Convert temperature to Kelvin

First, convert - 123°C to Kelvin. The conversion formula is $T(K)=T(^{\circ}C)+273.15$. So, $T=-123 + 273.15=150.15$ K. At 150.15 K and 20.9 atm, from the phase - diagram, the substance is in the solid state.

Step2: Calculate new pressure

The new pressure when decreased by 16.9 atm is $P = 20.9-16.9 = 4$ atm. At a temperature of 150.15 K and 4 atm, the substance changes from solid to gas (sublimation).

Step3: Calculate new temperature

The new temperature when decreased by 116°C from - 123°C: $T=-123-116=-239^{\circ}C$. Converting to Kelvin, $T=-239 + 273.15 = 34.15$ K. At 34.15 K and 20.9 atm, the substance remains in the solid state.

Answer:

Solid; Sublimation; Remains solid