Study of the effect of salt solutions on the kinetics of sucrose inversion as monitored by polarimetry

Abstract

The acid-catalyzed inversion of sucrose is often taken as an example of a first order reaction. It is, however, influenced by many factors such as temperature, type of acid used, concentration of sucrose, and the concentration of acid. What has received little attention so far is the influence of addition, in particular, other salts to the reacting solution. In this study, the influence of different salt solutions on the kinetics of sucrose inversion rate was studied at 29 °C by use of optical rotation measurements. The salts chosen for this study are readily soluble in sucrose solution and they provide an opportunity to study the interaction of electrolytes in aqueous solution of sucrose as well as their effects on the inversion of sucrose kinetics. The rates are found to be influenced by the concentration of the salts. No significant differences was measured when the salt were dissolved either in the sucrose or in the acid solutions. The influence of added salts to saccharide solutions was determined by evaluating the difference between the rotation of pure saccharides solutions and the rotation of pure saccharide solutions with salts. The changes in optical rotation were compared to the Hofmeister series. The saccharide-salt systems containing acidic salts (Na2HPO4 or NaH2PO4) were found to be dependent on the pH. Changing the molar ratio of sucrose and salt added also had an influence of the change in optical rotation.