Answer the following questions based on the P-T phase diagram of carbon dioxide : (a) At what temperature and pressure can the solid, liquid and vapour phases of CO_(2) coexist in equilibrium ? (b) What is the effect of decrease of pressure on the fusion and boiling point of CO_(2) ? (c) What are the critical temperature and pressure for CO_(2) ? What is their significance ? (d) Is CO_(2) solid, liquid or gas at (a) -70^(@)C under 1 atm, (b) -60^(@)C under 10 atm, (c) 16^(@)C under 56 atm ?

Answer the following questions based on the P-T phase diagram of carbo

1.	Answer the following questions based on the P-T phase diagram of carbon dioxide : (a) At what temperature and pressure can the solid, liquid and vapour phases of CO_(2) coexist in equilibrium ? (b) What is the effect of decrease of pressure on the fusion and boiling point of CO_(2) ? (c) What are the critical temperature and pressure for CO_(2) ? What is their significance ? (d) Is CO_(2) solid, liquid or gas at (a) -70^(@)C under 1 atm, (b) -60^(@)C under 10 atm, (c) 16^(@)C under 56 atm ?
Answer» SOLUTION :(a) From phase diagram of `CO_(2)` temperature of triple point `=-56.6^(@)C` and pressure `=5.11` atom (b) With decrease in pressure of `CO_(2)`, boiling and freezing points decreases. (c) Critical temperature of `CO_(2)` is `31.1^(@)C` and pressure is 73.0 atm. If it is compressed at HIGH temperature then this with pressure then it is not converted into liquid. (i) (`-70^(@)C,1.0` atm) point is in gaseous SECTION hence `CO_(2)` is in the gaseous state at this point. (II) `(-60^(@)C," 10 atm")` point is in solid section, hence `CO_(2)` is in solid state at this point. (iii) `(15^(@)C," 56 atm")` point is in liquid section, hence `CO_(2)` is in liquid state at this point.