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Chemical Engineering · Q384

Chemical Engineering Thermodynamics

Engineering and GATE · Chemical Engineering · question 384

Q384

Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is -57°C and 5.2 atm).

A.
Pressure must be kept below 5.2 atm
B.
Temperature must be kept above -57°C
C.
Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C
D.
Pressure and temperature must be kept below 5.2 atm. and -57°C respectively
Answer

Answer: Option D

Solution

Answer: Option D
Solution:
If we see the typical  plot any substance below the triple point we have only sublimation zone that means no liquefaction is not possible if we still decrease the pressure hence always the pressure should be greater than triple point pressure and the value of temperature depends on the pressure at which the substance is present.