PH a pH of 7.3. This is clearly wrong as an acid solution should have a pH of less than 7. Treating the system as a mixture of hydrochloric acid and the amphoteric substance water, a pH of 6.89 results. A weak acid or the conjugate acid of a weak base can be treated using the same formalism. First, an acid dissociation constant is defined as follows. Electrical charges are omitted from subsequent equations for the sake of generality and its value is assumed to have been determined by experiment. This being so, there are three unknown concentrations, [HA], [H] and
Casein paint or varnished for a gloss finish. The binder for casein paint is made by dissolving casein in an alkali, usually lime, ammonium carbonate, or borax. Casein itself is precipitated from milk by the action of an acid or the enzyme rennet. Lime casein works well on porous surfaces, even outdoors, though it has a short shelf-life and must be used with pigments that are balanced against the binder's low pH. Ammonium carbonate casein has similar strengths and weaknesses. Borax casein has a shelf-life of several weeks, is pH neutral, and can be used outdoors through the addition of linseed oil.