in which X is the fractional conversion, A is the Arrhenius preexponential factor, Ea is the activation energy, R is the gas constant, and T is the temperature. The fit to the data is shown in Figure . The underlying processes and rate-limiting step by which (LiNH2+2LiH) desorbs hydrogen are not fully understood. Thus, the Arrhenius parameters in Table should not be interpreted as corresponding to a particular reaction step.