For a weak monoprotic acid with

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

For a weak monoprotic acid with pKa=7.0pK_a = 7.0, which species is expected to predominate in a solution whose pH is 5.0? (a) The deprotonated form, A−A^-, because [A−]/[HA]=102[A^-]/[HA]=10^{2} when the pH is two units different from the pKapK_a. (b) The protonated form, HAHA, because pH is below pKapK_a. (c) There is insufficient information to determine which species predominates because the acid’s concentration is not specified. (d) The deprotonated form, A−A^-, because pH is below pKapK_a.

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