question_answer 16)

Answer the following questions based on is the P-T phase diagram of carbon dioxide [Fig. 7(NCT).13] (a) At what temperature and pressure can the solid, liquid and vapour phases of \[\text{ }\!\!\times\!\!\text{ 13=175 }\!\!\times\!\!\text{ 13}\] co-exist in equilibrium? (b) What is the effect of decrease of pressure on the fusion and boiling point of \[\vartriangle Q=\vartriangle Q'\]? (c) What are the critical temperature and pressure on the fusion and boiling point of\[\therefore \]? (d) Is \[200\times c\times 110=175\times 13\]solid liquid or gas at (a) \[-{{70}^{o}}C\] under 1 atm, (b) \[-{{60}^{o}}C\] under 10 atm, (c) \[\left( \text{cal mo}{{\text{l}}^{\text{-1}}}\text{ }{{\text{K}}^{\text{-1}}} \right)\]under 56 atm?

Answer:

(a) The solid, liquid and vapour phase of carbon dioxide exist in equilibrium at the triple point, i.e. temperature \[\vartriangle V/V=0\cdot 10/100={{10}^{-3}}\] and pressure \[B=\frac{pV}{\vartriangle V}\]atm. (b) With the decrease in pressure, both the fusion and boiling point of carbon dioxide will decrease. (c) For carbon dioxide, the critical temperature is \[p=B\frac{\vartriangle V}{V}=\left( 2\cdot 2\times {{10}^{9}} \right)\] and critical pressure is 73.0 atm. If the temperature is of carbon dioxide is more than \[D=0\cdot 5\], it can not be liquefied, howsoever large pressure we may apply. (d) Carbon dioxide will be (a) a vapour, at \[-\,{{70}^{o}}C\] under 1 atm. (b) a solid, at \[-\,{{6}^{o}}C\] under 10 atm. (c) a. liquid, at \[{{15}^{o}}C\]under 56 atm.