The Infrared Absorption of Acid Solutions

Abstract

A study has been made of the absorption of aqueous solutions of HCl, HF, HBr, H2SO4, HNO3, NaCl and NaBr in the region from 1.7μ to 6.5μ. Also HCOOH, C6H5COOH have been studied from 5μ to 6.5μ. No absorption bands were found for HCl and HBr in the regions of 3.5μ and 3.8μ, respectively, where there are strong bands in the gaseous state. All of the acid solutions showed a strong band at about 5.5μ. The position of this band varied slightly with the solute and the sharpness of the band was different for each acid. Another band was found at 2.40μ for the solutes. The 5.5μ band is explained as due to the undissociated molecule attached to a water molecule and the 2.40μ band as due to the same effect or to a hydrogen ion attached to a water molecule.