How long does a nitrogen tetroxide molecule typically last at room temperature and atmospheric pressure?

At room temperature and atmospheric pressure, a nitrogen tetroxide molecule has an average lifetime of approximately one-third of a microsecond (one-millionth of a second).1

This duration is a key aspect of chemical relaxation, as the molecule exists in a dynamic equilibrium with nitrogen dioxide. In this state, the dissociation of the dimer (nitrogen tetroxide) into two monomers (nitrogen dioxide) is exactly balanced by the rate at which the monomers recombine. Because systems at equilibrium cannot respond instantaneously to external changes in temperature or pressure, the finite time required for the mixture to reach a new equilibrium concentration is known as the relaxation time.21