pH值最简计算公式的使用条件及计算结果的修正

本文提出的酸碱溶液pH值计算最简公式使用条件,比前人提出的简单、条理化,便于记忆,应用方便。当不能满足使用条件时,还可用本文提出的修正法。这样,计算时仍可使用最简公式。修正法也很简单,只要从两条曲线上去找修正值就行了。

The Application Conditions of Approximate pH Calculation Formulae and the Correction of Calculated Results

The application conditions of approximate pH calculation formulae, which is easier to remember and use than those reported previously, can be concluded as follows.1. Acid solutions. Use the formulae H+]= Kwi H+ ] = H+ ] = CHA to calculate the pH values of the solution, while all the solvent, weak acids and strong acid are regarded as presented independantly. ( 1 ) In strong acid system, if all the pH values calculated by the Kw, KaCHB are 0.64 or higher than the pH value calculated by H+] = CHA, the pH value of the solution equals to CHA. ( 2 ) In weak acids system, if the calculated pH of the solvent and other weak acids are 0.50 or more larger than the pH value of the main weak acid calculated by KaCHB, and the pH>the pH = KaCHB is true.2. Ampholyte solutions. Use the formulae H+ ] = Ka2CHB, H+ ] = Ka1Ka2, H+] = Kw to calculate the pH value. If the pH value calculated by KazCHB is 0.5 or lower than the others, the pH value of ampholyte solution may be calculated by H+ ] = Ka1Ka2It i sy to correct the results when the application conditions are not met. The correction values can be found on two correction curves. Some examples are given.