The kinetics of the absorption of phosgene into water and aqueous solutions

Abstract

AbstractPure phosgene gas was dissolved in short laminar jets of aqueous solution, and the results were interpreted with an unsteady state absorption‐plus‐reaction theory. Absorption rates of sulfur dioxide and carbon dioxide into water in the same equipment support this interpretation. The solubility of phosgene in water at 25°C. has been estimated from the absorption rates as 0.069 g.mole/(liter) (atm.). The estimated heat of solution is 6,800 cal./g.mole. At 16° and 25°C. the effect of a chemical reaction between phosgene and water on the absorption rate in a jet appears to be almost negligible, but at 45°C. a first‐order reaction rate constant of 75 sec.−1 can be derived from the absorption rates.From absorption measurements with short jets and sodium hydroxide solutions so strong that a pseudo‐first‐order reaction accompanied absorption, the reaction rate constant for the bimolecular reaction between dissolved phosgene and the hydroxyl ion was estimated. A value of 1.6 × 104 liters/(g. mole) (sec.) was obtained at 25°C. in 1‐N sodium hydroxide; at 35°C. in the same solution the estimated value was 2.9 × 104. There appears to be a slight increase in the reaction‐rate constant with the ionic strength of the solution.