The Infra-Red Absorption Spectra of Alkali Hydroxides

Infra-red Absorption of Aqueous Solutions of Alkali Hydroxides, I-3μ.—The absorption of various concentrations of solutions of NaOH, KOH and LiOH and of one solution each of N${\mathit{H}}_4$OH and CsOH was determined with reference to that of water, using two like cells with quartz windows, and a suitable spectrometer with thermopile and sensitive galvanometer. All curves show a broad, intense absorption band with a maximum at about 2.29μ except in the case of the N${\mathrm{H}}_4$OH solution for which the maximum is at 2.20μ. This agreement suggests that the band is due to dissociated hydroxide ions; yet in the case of other hydroxide solutions previous observers have not obtained an absorption band at this place. The absorption was found to be proportional to the concentration but not to vary systematically with the atomic weight of the base of the hydroxide. In the case of KOH the relative absorption results were checked by actual absorption measurements.