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From p"K"[subscript a] to the pH of Weak Base Solutions
Ist Teil von
Biochemistry and molecular biology education, 2020-05, Vol.48 (3), p.259-261
Ort / Verlag
Wiley-Blackwell
Erscheinungsjahr
2020
Link zum Volltext
Quelle
Wiley Online Library Journals Frontfile Complete
Beschreibungen/Notizen
Undergraduate biochemistry students frequently find the quantitative treatment of weak acids and bases troublesome. Given the p"K"[subscript a] of a weak acid "HA," for instance, many students struggle to calculate the pH of a solution of the conjugate base A[superscript -] at concentration "C," pH(A[superscript -], "C"). The traditional method involves calculating the base dissociation constant "K"[subscript b] 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 p"K"[subscript a] of its conjugate acid without calculating "K"[subscript b] and pOH, using a memorable relationship: pH(HA, "C") + pH(A[superscript -], "C") = p"K"[subscript a] + 7.