Effect of Bromine Derivatives of Malonic Acid on the Oscillating Reaction of Malonic Acid, Cerium Ions and Bromate

Abstract

WHEN malonic acid, ceric sulphate and potassium bromate are dissolved in dilute sulphuric acid there occurs an oscillating chemical reaction which manifests itself by an oscillation of the light absorption which is caused by ceric ions (317 mµ) and an oscillation of the rate of evolution of carbon dioxide. An oscillation of the potential of a platinum electrode dipped into the solution can also be measured¹. Fig. 1 shows the light absorption at 317 mµ as a function of time in a solution of the above mentioned substances. The curve divides itself into four distinct sections: (a) disappearance of ceric ions; (b) reappearance of ceric ions; (c) stationary concentration of ceric ions; (d) oscillation. The cessation of the oscillation (not shown in Fig. 1) is usually abrupt, and the ceric ion concentration persists at the minimal value attained in the oscillation.