Answer to Question #328605 in General Chemistry for Bea

Question

1. YYouhave ice at 263 K (-10.0 oC) and 1.0 atm. What could you do to make the ice sublime?

2. A sample of dry ice (solid CO2) is cooled to 173 K (-100.0 oC), and is set on a table at room

temperature (298 K; 25 oC). At what temperature is the rate of sublimation and deposition the same (assume that

pressure is held constant at 1 atm)?

3. What are the significant differences between the phase diagrams of water and carbon dioxide? Discuss

each briefly.

Answer 1

The temperature at which these processes occur at 1 atm pressure is 194.65 K. The temperature at which the rate of sublimation and deposition are the same is the temperature at which these two processes are in equilibrium (this temperature is the freezing point, or sublimation point of CO₂).

In contrast to the phase diagram of water, the phase diagram of CO₂ has a more typical melting curve, sloping up and to the right. The triple point is −56.6°C and 5.11 atm, which means that liquid CO₂ cannot exist at pressures lower than 5.11 atm.