混合弱酸溶液缓冲容量的计算方法研究

缓冲溶液是无机化学及分析化学的教学重要内容。推导了两种三元弱酸组成缓冲溶液的缓冲容量公式,发现了缓冲容量的加和性。通过Excel计算了0.10 mol/L柠檬酸-0.10 mol/L磷酸以及克拉克-鲁布斯(Clark-Lubs)缓冲溶液(邻苯二甲酸、磷酸和硼酸的物质的量浓度均为0.20 mol/L)在不同pH值的缓冲容量,图示了缓冲容量随pH值的变化曲线,直观说明了上述缓冲溶液的缓冲范围。结果表明,柠檬酸和磷酸缓冲溶液在pH<8时具有很好的缓冲作用,Clark-Lubs缓冲溶液在pH<10时具有很好的缓冲作用。

Study on the calculation method of buffer capacity of mixed weak acid solution

The buffer solution is an important teaching content in inorganic chemistry and analytical chemistry. The calculation formula of buffer capacity of two buffer solutions composed of triptotic weak acids was deduced, and the additivity of buffer capacity was discovered. The buffer capacity of 0.10 mol/L citric acid-0.10 mol/L phosphoric acid and Clark-Lubs buffer solution (0.20 mol/L phthalic acid-0.20 mol/L phosphoric acid-0.20 mol/L boric acid) under different pH conditions was calculated by Excel. The changing curve of buffer capacity against pH was graphically displayed. The buffer range of buffer solutions above was intuitively shown. The results indicated that the citric acid-phosphoric acid buffer solution had good buffer effect at pH<8, while Clark-Lubs buffer solution exhibited good buffer effect at pH<10.