91Ó°ÊÓ

Polymerization. Consider a polymerization reaction in the gas phase in which \(n\) moles of identical monomers are in equilibrium with one mole of chains of \(n\)-mers: $$ n(0) \stackrel{\frac{k}{\longrightarrow}}{\underbrace{0-0-0-0}_{n \text { monomers }}} $$ (a) Do you expect typical polymerization processes to be driven or opposed by enthalpy? By entropy? What are the physical origins of these enthalpies and entropies? (b) Do you expect polymerizations to be exothermic (giving off heat) or endothermic (taking up heat)? Explain the explosions in some polymerization processes. (c) Are polymerization equilibrium constants for long chains more or less sensitive to temperature than those for shorter chains?