The Electron Affinity of Bromine and a Study of Its Decomposition on Hot Tungsten

The electron affinity of bromine has been measured by determining the ratio of ions to electrons leaving a hot tungsten surface in contact with bromine gas at low pressure. The value obtained is 80.5±0.4 kcal./mole. The measurements, which extend over a range of 700° in temperature and 80-fold in pressure, show no trend in the electron affinity and demonstrate that the decomposition of bromine under these conditions is a first-order reaction. The assumption of unit accommodation coefficient is shown to be correct.