Ka2+4cKa+4c）出发，推导出了计算氢离子浓度的其他2个近似公式：（1）c越小，[H+]AV1越趋向c。计算表明，当满足c≤1/19Ka和c≥5.0×10-7 mol/L时，弱酸HA就可作强酸处理，此时得到近似式[H+]AV4=c，这极大简化了弱酸溶液氢离子浓度的计算。（2）c越大，[H+]AV1越接近√cKa。当满足c≥105Ka和cKa≥10Kw时，弱酸溶液氢离子浓度可按最简式[H+]AV2=√cKa计算。还解释了c≥105Ka和c≤1/19Ka时所包含的物理意义。需要强调的是，本文首次给出了各近似式的浓度适用范围，比如忽略水的解离时，除了满足cKa≥10Kw，还必须要求c≥6.0×10-6 mol/L。"/>
Ka2+4cKa), other two equations can be derived directly:(1) when c approaches 0,[H+]AV1 approaches c. In fact, when c ≤ 1/19Ka and c ≥ 5.0×10-7 mol/L, HA can be treated as a strong acid, namely[H+]=c. (2) when c approaches very large,[H+]AV1 approaches √cKa. In fact, when c ≥ 105Ka and cKa ≥ 10Kw, the hydrogen ionic concentration of the HA solution can be obtained by[H+]AV2=√cKa. Another purpose of this article is to discuss the working conditions of various approximations in detail. For example, if approximate equation[H+]AV1=1/2(-Ka+√Ka2+4cKa) works properly, both c ≥ 6×10-6 mol/L and cKa ≥ 10Kw should be fulfilled."/>
数学方法推导一元弱酸溶液氢离子浓度的近似公式及适用条件
