Question

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 CO2 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 at (a) –70 °C under 1 atm, (b) –60 °C under 10 atm, (c) 15 °C under 56 atm?

Answer 1

(a) the solid , liquid and vapour phase of CO2 can exist in equilibrium at its triple point O, corresponding to which
Pressure (P) = 5.11 atm
Temperature ( T) = -56.6°C

(b) curve I shows vaporisation curve .
Curve II shows fusion curve. Both the graph shows that boiling point and fusion point of CO2 decrease with decrease of pressure .

(c) For CO2,
Critical pressure = 73 atm
Above critical temperature= 31.1°C
CO2 gas can't be liquified above critical temperature ( 31.1°C) , if pressure is very high .

(d) (i) CO2 is vapour at -70°C and 1 atm as this point lies in vapour region .
(ii) CO2 is solid at -60°C and 10 atm as this point lies in solid region .
(iii) CO2 is liquid at 15°C and 56 atm as this point lies in liquid region .

Answer 2

______✨ HEY MATE ✨______

➡️(a) the solid , liquid and vapour phase of CO2 can exist in equilibrium at its triple point O, corresponding to which

Pressure (P) = 5.11 atm

Temperature ( T) = -56.6°C

(b) curve I shows vaporisation curve .

Curve II shows fusion curve. Both the graph shows that boiling point and fusion point of CO2 decrease with decrease of pressure .

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