When a sample of carbon dioxide (CO2) is subjected to a pressure of 10 atm and heated from 80°C to 40°C, we can analyze the phase diagram of CO2 to determine the phases present during this temperature change.
At 10 atm, CO2 predominantly exists in its liquid state at higher temperatures. As we start heating at 80°C, we are above the sublimation point of CO2 but still below its critical point, which means CO2 is in the supercritical phase under these conditions. This phase will transition as the temperature decreases because it doesn’t pass through the phase where solid or gas appears at lower pressures.
As we move from 80°C to 40°C, we remain above the melting point and below the critical temperature, so the CO2 is expected to remain in a liquid state initially. However, approaching 40°C, if the pressure remains constant at 10 atm, it could eventually lead to some transition into the gaseous state depending on specific phase diagram behavior, although at 10 atm both liquid and gas phases could coexist and stabilize still depending on the exact points of the heating.
Conclusively, during this heating process, we can observe the liquid phase of CO2 primarily at these conditions, without entering the solid phase given the temperatures dictated.