Extensive measurements of the gel point were performed by Flory using diethylene glycol and adipic acid in the presence of different amounts of 1,2,3-propanetricarboxylic acid. One run was performed under the following conditions: 0.5 mol. adipic acid, 1.0 mol. diethylene glycol and 0.20 mol. 1,2,3-propanetricarboxylic acid. a. According to the Flory theory of gelation, at what extent of reaction, pA (with respect to the carboxyl groups) is the gel point reached? (10 points) b. Gelation was experimentally observed at pA = 0.991 (i.e. when 99.1% of the carboxyl groups had reacted). How does this extent of reaction compare with the predicted value of part a? At the gel point, what is the experimental value of the branching coefficient, c? (10 points) c. What is the number average degree of polymerization at the theoretical gel point which is predicted by the theory? (10 points) Hint: Use the regular definition of the number average degree of polymerization, ; x n (x n )t = Total # of structural units in system Total # of molecules @ time t