Significance of the solubility of hydrogen halides in liquid compounds

The solubilities of hydrogen halides (HCl, HBr, HI), expressed as x HX moles of HX per mole of a liquid compound, have been determined for a representative selection of compounds at room temperature and below to reveal an essential pattern of behaviour to serve as a guide in operational procedures. Compared with the values predicted by Raoult's law at 0° ( x HCl = 0.04, x HBr = 0.09, x HI = 0.37), liquids such as n‐heptane and carbon tetrachloride have slightly lower x values, but show increasing divergence on the low side as the temperature is lowered. Other liquids, such as toluene and alkyl halides, have values greater than those predicted by Raoult's law at 0°, and x HX remains correspondingly higher at the lower temperatures. The x HX values for many liquids can be from 2 to 6 times as great as those for water: x HCl = 0.41, x HBr = 0.49, x HI = 0.39 at 0°. From a consideration of pressure and other effects, a reference pattern of the constitution of the solutions is given. For the non‐aqueous liquids, x HX values greater than Raoult's law values are deemed to be the result of definite chemical reactions involving hydrogen bonding and dynamic equilibria. A case is presented for the desirability of the readjustment of attitudes towards acid‐base function in operational chemistry.