Question

Question 20

The production of polyvinyl chloride, a common type of plastic, is produced by the reaction of chlorine gas and ethene, according to the reaction

Cl_{2 (g)} + H₂C=CH_{2 (g)} → ClCH₂CH₂Cl_(l)

and the enthalpy change for the reaction is -52 kcal/mol. Is this reaction spontaneous at all temperatures?

Yes, it is spontaneous at all temperatures.

   No, it is non spontaneous at all temperatures.

   It is non-spontaneous at high temperatures and spontaneous at low temperatures.

   

Answer 1

Ans : It is non-spontaneous at high temperatures and spontaneous at low temperatures.

The change in entropy for this reaction is negative , as the gaseous reactants are changed into liquid products.

The spontaneity of a chemical reaction is decided by its gibbs free energy change , if negative then the reaction is spontaneous and if positive than the reaction is non spontaneous.

Here both entropy and enthalpy are negative , so the reaction is spontaneous at low temperatures and nonspontaneous at high temperatures.