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 - 159. °c and 2.1 atm. what will be the state of the sample? suppose the temperature is held constant at - 159. °c but the pressure is decreased by 1.7 atm. what will happen to the sample? suppose, on the other hand, the pressure is held constant at 2.1 atm but the temperature is increased by 45. °c. what will happen to the sample?

Explanation:

Step1: Convert temperature to Kelvin

First, convert - 159°C to Kelvin. The conversion formula is $T(K)=T(^{\circ}C)+273.15$. So, $T = - 159+273.15=114.15$ K. At 114.15 K and 2.1 atm, from the phase - diagram, the state of the sample is solid.

Step2: Calculate new pressure

The new pressure is $P = 2.1 - 1.7=0.4$ atm. At a temperature of 114.15 K and pressure of 0.4 atm, the sample will change from solid to gas (sublimation).

Step3: Calculate new temperature

The new temperature is $T=-159 + 45=-114^{\circ}C$. Convert to Kelvin: $T=-114 + 273.15 = 159.15$ K. At a pressure of 2.1 atm and temperature of 159.15 K, the sample will change from solid to liquid (melting).

Answer:

1. Solid
2. Sublimation (change from solid to gas)
3. Melting (change from solid to liquid)