Answer the following questions based on the p-T phase diagram of CO2:
(a) At what temperature and pressure can be solid, liquid and vapour phases of CO2 and CO exist in equilibrium?
(b) What is the effect of decrease of pressure on the fusion and boiling point of CO2?
(c) What are the critical temperature and pressure for CO2? What is their significance?
(d) Is CO2 solid, liquid or gas (a) -70°C under 1 atm, (b) -60°C under 10 atm, (c) 15°C under 56 atm.