To determine the phase of carbon dioxide (CO₂) at a temperature of -60°C and a pressure of 15 atm, we need to refer to the phase diagram of CO₂. Here are the steps for analyzing the information:
1. Understand the Basics of the Phase Diagram:
- A phase diagram depicts the state of a substance at various temperatures and pressures.
- Key points on the phase diagram include the triple point, the sublimation point, and critical points.
2. Identify Key Points for CO₂:
- The triple point of CO₂ is at -56.4°C and 5.11 atm. At this point, solid, liquid, and gas phases coexist in equilibrium.
- The sublimation point is where CO₂ transitions directly from solid to gas.
3. Given Conditions:
- Temperature: -60°C
- Pressure: 15 atm
4. Analyze the Conditions Relative to the Phase Diagram:
- The temperature of -60°C is below the triple point temperature of -56.4°C. This means we are in the region where CO₂ would typically be found as a solid if the pressure were also below the triple point pressure.
- The pressure of 15 atm is significantly above the triple point pressure of 5.11 atm. This high pressure tends to favor the formation of a solid phase at such a low temperature.
5. Conclusion Based on the Given Conditions:
- At -60°C (which is colder than the triple point temperature) and at 15 atm (which is higher than the triple point pressure), CO₂ remains in the solid phase.
Therefore, considering the information from the phase diagram for CO₂ and the given conditions:
The phase of carbon dioxide at -60°C and 15 atm is:
A. Solid
