## Analysis of Composition to Determine the Strongest Buffer Capacity in the Buffer Solution

Wang Tongwei,

Abstract

In a variety of the inorganic chemistry teaching materials and related references that the composition to give the strongest buffer capacity at pH=pKaϴ is not described concisely. We proposed amendment description for buffer capacity in the book written by teaching and research office of Inorganic Chemistry at Dalian University of Technology. The description is based on the distribution curve slope when buffer solution pH as close as possible to pKaϴ.

Keywords： Inorganic chemistry ; Buffer solution ; Buffer capacity

Wang Tongwei. Analysis of Composition to Determine the Strongest Buffer Capacity in the Buffer Solution. University Chemistry[J], 2021, 36(6): 2101038-0 doi:10.3866/PKU.DXHX202101038

## 1 问题

### 2.1 绘制醋酸和醋酸根的分布曲线

Kaϴ(HAc)= {c(H3O+)}·{c(Ac-)}/{c(HAc)}，即：{c(Ac-)}/{c(HAc)}= Kaϴ(HAc)/{c(H3O+)}。

### 2.2 分布曲线斜率意义

δ(HA或A-)与缓冲溶液pH分布曲线的斜率数学表示为Δδ(HA或A-)/ΔpH，对由定量醋酸和醋酸根所构成的缓冲溶液，其溶液中存在c(HAc) + c(Ac-) =常数。

### 2.3 以Ac-为例求算分布曲线斜率的最值

= 1/{1/[10-pH/Kaϴ(HAc)] + 10-pH/Kaϴ(HAc) + 2}。

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