The Phase Diagram for CO₂ Has a Triple Point at -56.6

question 11

Multiple Choice

The phase diagram for CO₂ has a triple point at -56.6 ^$\circ$ C and 5.19 atm,and a critical point at 31.0 ^$\circ$ C and 73 atm.The solid and gas phases are in equilibrium at -78.7 ^$\circ$ C and 1.00 atm.Which of the following statements regarding CO₂ is/are CORRECT?
1) Sublimation occurs if the temperature of the solid phase is increased from -79.0 ^$\circ$ C to 0.0 ^$\circ$ C at a constant pressure of 2.5 atm.
2) CO₂ is a supercritical fluid at 55 ^$\circ$ C and 75 atm.
3) At pressures greater than its critical pressure (73 atm) ,CO₂ will not exist as a solid at any temperature.

• A) 1 only
• B) 2 only
• C) 3 only
• D) 1 and 2
• E) 1,2,and 3