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The lumping of a complex mixture into a continuum first proposed by DeDonder (1931) has found a number of applications Ark, 1966). A particularly simple form was applied to cracking (Aris, 1968) and it was shown that parallel first-order cracking of a continuum could simulate any reaction order between one and two. Specifically let on the assumption of an exponential distribution since it was propounded in the context of reaction (Gavalas andor something like it. and the total remaining fraction isBut thenIf c(") (0, 0) < KT", this converges for t > T, but in any casegives us an asymptotic series of which the leading term is C ( t ) -is the apparent order of reaction. As a increases from 1 to infinity, / 3 decreases from 2 to 1. Apparent second-order reaction, a phenomenon somewhat implausible in itself, becomes plausible and the equivalent second-order rate constant is l/c(o, 0). Thus the presence of a finite fraction that is virtually unreactive leads always to apparent second-order kinetics for this "lump." This is