The reactions of electrons and positive holes with neutral scavenger molecules in nonpolar liquids have been considered. Those cases where the yield G(P) of scavenged electrons or holes per 100 eV of ionizing radiation absorbed follows the empirical formula G(P) = G/sub fi/ + G/sub gi/(..cap alpha../sub s/c/sub s/)/sup 1/2/(1 + (..cap alpha../sub s/c/sub s/)/sup 1/2/)/sup -1/, where c/sub s/ is the scavenger concentration, G/sub fi/ and G/sub gi/ are the free ion yield and gemate ion yield, respectively, and ..cap alpha../sub s/ is an empirical parameter, called the reactivity, which is characteristic of a given solvent--scavenger system have been explicitly analyzed. By combining this formula with the diffusion theory of Magee and Tayler, the following formula: ..cap alpha../sub s//k/sub s/ = (r/sub c//sup 2//D)(G/sub fi//G/sub gi/)/sup 2/ has been obtained for the ratio ..cap alpha../sub s//k/sub s/. Here k/sub s/ is the bimolecular rate constant for reaction of the electron or hole with the scavenger, D is the sum of the electron and hole diffusion coefficients, and r/sub c/ = e/sup 2//epsilonkT, where e is the charge of the electron, k is Boltzmann's constant, T is the absolute temperature, and epsilon is the liquid dielectric constant. For electron scavengersmore » in cyclohexane, n-hexane, and isoctane, at T = 296K, experimental values for ..cap alpha../sub s//k/sub s/ are known and are in satisfactory agreement with the ratio formula. For 14 other liquidsat T = 296K the formula predicts that ..cap alpha../sub s//k/sub s/ lies in the range of 0.04 to 155 ps. The formula also allows the temperature dependence of ..cap alpha../sub s//k/sub s/ to be assessed. For propane at T = 148, 183, and 230K, values of ..cap alpha../sub s//k/sub s/ of 47,0.7, and 0.1 ps, respectively were calculated. Although the ratio formula is specific to the representation of G(P) above, this method of derivation can be applied to any representation of G(P) so long as it is an analytic function of c/sub s//sup 1/2/.« less