Question

Is the enthalpy of the Diels-Alder reaction positive or negative? Is the entropy of the Diels-Alder reaction positive or negative? In each case, clearly explain why it is positive or negative.

Answer 1

a) Entropy: negative

In this reaction, the degree of freedom decreases as the reactants are converted into the products. The reactions therefore, represents an example of decrease in entropy, S is negative.

no of product moles < no of reactant moles

b) Enthalpy : positive

in order to diels alder reaction occur we need to supply heat of light . diels alder reaction some are thermally allowed and some are photochemically allowed. in both cases heat must be supplied so it is Endothermic