Chemistry

Chemistry

Problem

Fifty milliliters of 0.100 M pyridine (a weak base) is titrated with 0.100 M HCl. Calculate the pH after 55.0 mL of the acid has been added. a) 2.042.04 b) 2.322.32 c) 5.235.23 d) 1.281.28
Intuitive explanation

You're past the equivalence point, so the key is recognizing that excess strong acid dominates the pH. Calculate moles of pyridine and HCl added, find how much HCl remains unreacted, then treat that excess as the source of H+H^+ ions. The weak conjugate acid (pyridinium ion) present won't meaningfully affect pH when a strong acid is in excess.

Intuitive explanation

You're past the equivalence point, so the key is recognizing that excess strong acid dominates the pH. Calculate moles of pyridine and HCl added, find how much HCl remains unreacted, then treat that excess as the source of H+H^+ ions. The weak conjugate acid (pyridinium ion) present won't meaningfully affect pH when a strong acid is in excess.

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