BODENSTEIN , MAX ERNST AUGUST

Bodenstein, who was born in Magdeburg, Germany, gained his doctorate at Heidelberg (1893). He subsequently worked with Wilhelm Ostwald at Leipzig before becoming a professor at Hannover (1908–23) and at the Institute for Physical Chemistry, Berlin (1923–36). He made a series of classic studies on the equilibria of gaseous reactions, especially that of hydrogen and iodine (1897). His technique was to mix hydrogen and iodine in a sealed tube, which he placed in a thermostat and held at a constant high temperature. The reaction eventually reached an equilibrium, at which the rate of formation of hydrogen iodide (HI) was equal to the rate of decomposition to the original reactants: H₂ + I₂⇌ 2HI

The equilibrium mixture of H₂, I₂, and HI was ‘frozen’ by rapid cooling, and the amount of hydrogen iodide present could be analyzed. Using different amounts of initial reactants, Bodenstein could vary the amounts present at equilibrium and verify the law of chemical equilibrium proposed in 1863 by Cato Guldberg and Peter Waage.

Bodenstein also worked in photochemistry and was the first to show how the large yield per quantum for the reaction of hydrogen and chlorine could be explained by a chain reaction.