Estimate the orders of magnitude of the partition functions involved in a rate expression. State the order of magnitude of q INA, qR, qV, qE for typical molecules. Check those in the collision of two structure less molecules the order of magnitude of the pre-exponential factor is of the same order as that predicted by collision theory. Go on to estimate the P factor for a reaction in which A + B → P, and A and Bare nonlinear triatomic molecules.