弱酸PC-PH图的特征及简便画法

The characteristics and simple drawing method of PC-PH diagram of weak acid

本文根据25℃时一元弱酸HA、二元弱酸H_2B的PC-PH图,得出了弱酸PC-PH图的一般特征和简便画法。结果表明:弱酸PC-PH图的控制条件为系统点(PH=PK_a,PC=PC_T)、各物种浓度线的斜率和镜像轴PH=PK_a。此结果对于该弱酸的共轭碱或者该弱酸与其共轭碱的混合物同样适用。

In this paper,the general characteristics and simple drawing method ofPC-PH diagram of the weak acid was obtained according tothe PC-PH diagrams of monprotic acid（HA） and polyprotic acid （H2B） at 25 ℃ . The results showed thatthe control condition of cphdiagram are the system point （PH=PKa, PC=PCT）, the slope of each species concentration line and the mirror axis PH=PKa. This result applies to the conjugate base of the weak acid-conjugate base systems and its conjugate base.