Question

What would you observe if you heated solid carbon dioxide from a very low temperature at 7,387kPa?

a) Solid carbon dioxide would sublimate directly into a gas.
b) Solid carbon dioxide would melt into a liquid.
c) Solid carbon dioxide would decompose into carbon and oxygen gases.
d) Solid carbon dioxide would remain unchanged.

Answer 1

The Correct option is A). At 7,387kPa, solid carbon dioxide would sublimate directly into a gas because this pressure is significantly higher than CO₂'s triple point, precluding the formation of a liquid phase.

Step-by-step explanation:

If you heated solid carbon dioxide from a very low temperature at 7,387kPa, you would observe that the solid carbon dioxide sublimates directly into a gas. This is because the phase diagram of CO₂ indicates that at pressures over 5.11 atm (5171.15 kPa), which is above the pressure in question, the solid phase goes directly into the vapor phase without entering the liquid phase at temperatures below the critical point. The triple point of carbon dioxide is at -56.6°C and 5.11 atm, and since 7,387kPa is significantly above this pressure, it ensures that liquid CO₂ does not form under the conditions described. Instead, sublimation occurs, where CO₂ (s) changes directly to CO₂ (g).