Answer the following question beased on tbhe P-T phase diagram of carbon dioxide.

(a) At what temperature and pressure can the solid, liquid and vapour phases of `CO_2` co-exist is equilibrium ? (b) What is the effect of decrease of pressure on the fusion and bolling point of `CO_2` ? (c ) What are the critical temperature and pressure for `CO_2` ? What is their significane ? (d) Is `CO_2` solid, liquid or gas at (a) ` -70^@C` under 1 atm, (b) `-60^@C` under 10 atm, (c) `15^@C` under 56 atm ?

Explanation

At the triple point temperature ` = - 56.6 ^(@) C` and pressure = `5.11` atm.