We use molecular dynamics to determine the force needed to rupture a chain molecule being stretched at constant loading rate and temperature. When all energy bonds of the molecule are identical, we find that the force F depends on the pulling rate r and temperature T according to F approximately const- T(1/3)|ln (r/T)|(1/3). When a single weak bond is introduced, this result is modified to F approximately const - T(2/3|ln (r/T)(2/3)|. This scaling, which is model independent, can be used with experiment to quantitatively extract relevant microscopic parameters.