To clarify the effect of microwave irradiation on acceleration of chemical reactions other than heating, Arrhenius' plots were taken for the disintegration reaction of sodium hydrogen carbonate water solution. Then to observe the influence of microwave field on the reaction, gas-generating velocities with different irradiated microwave powers were measured under a constant temperature condition. As a result, it was recognized that the micron ave field acts to decrease the activation energy of the reaction. Next, pulsed and CW microwave powers, both having the same mean power, were applied to the solution and the pulsed microwave field was observed to accelerate disintegration more than CW. Although the molecular mechanism is not clear, a decrease of the activation energy seems to accelerate the reaction.
