Apply the Gibbs phase rule to determine the number of independent primary reactions needed to calculate the equilibrium composition of the butadiene system at a given T, P, and the initial composition of the reactants. I really like the reaction pathway shown below to demonstrate different aspects of kinetic versus thermodynamic phenomena. intermediate state 3-bromo-1-butene (20) HBr Butadiene carbonium ion (22) Br 1-bromo-2-butene (21) (a) T=-80 C T- 40C 3-bromo-1-butene 3-bromo-1-butene (20) fast (20) Less stable Butadiene Butadiene 1-bromo-2-butene (21) 1-bromo-2-butene (21) More stable Kinetics controls the reaction Thermodynamics control the reaction (b)