Question

Arrange the following substances in order of decreasing vapor pressure. Assume you are comparing them at –190°C where all three are solids. CF Naci Sici, Reset

Answer 1

At a given temperature, and in a closed vessel, when the pressure is exerted by a vapor in equilibrium state with its condensed phases, then it is called Vapor pressure.

NaCl has Ionic forces which are stronger than covalent forces. And therefore, it is difficult for molecules to move to vapor phase and it has Lowest vapor pressure among the given molecules.

SiCl4 has Cl-atoms which has lower electronegativity values as compared to F-atoms and therefore they show poorly polarized bonds and observe highest vapor pressure.

The correct order of decreasing vapor pressure is: SiCl4 > CF4 > NaCl.

The detailed solution is given below:

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