Department of Biological Sciences, Royal Holloway, University of London, Egham, UK.
Biochem Mol Biol Educ. 2020 May;48(3):259-261. doi: 10.1002/bmb.21336. Epub 2020 Feb 10.
Undergraduate biochemistry students frequently find the quantitative treatment of weak acids and bases troublesome. Given the pK of a weak acid HA, for instance, many students struggle to calculate the pH of a solution of the conjugate base A at concentration C, pH(A , C). The traditional method involves calculating the base dissociation constant K and the artificial quantity pOH before reaching pH, but these steps increase the risk of mistakes and provide little insight into acid-base equilibria. The alternative method presented here allows students to calculate the pH of a weak base solution from the pK of its conjugate acid without calculating K and pOH, using a memorable relationship: pH(HA, C) + pH(A , C) = pK + 7.
本科生物化学专业的学生经常发现，对弱酸和弱碱进行定量处理很麻烦。例如，给定弱酸 HA 的 pK 值，许多学生在计算浓度为 C 的共轭碱 A 的溶液的 pH 值 pH(A, C)时遇到困难。传统方法涉及计算碱基离解常数 K 和人工量 pOH，然后才能得到 pH 值，但这些步骤增加了出错的风险，并且对酸碱平衡几乎没有深入的了解。这里提出的替代方法允许学生从其共轭酸的 pK 值计算弱碱溶液的 pH 值，而无需计算 K 和 pOH 值，使用一个易于记忆的关系：pH(HA, C) + pH(A, C) = pK + 7。
