Should pH = pKa at half-equivalence be taught as fact or approximation?
I've titrated countless weak acids in the lab, and the assumption that pH exactly equals pKa at the half-equivalence point still holds up remarkably well. Yet textbooks present it as an immutable law, ignoring that ionic strength and temperature shifts can skew the reading by 0.1–0.2 units. Should we keep teaching this approximation as a hard rule, or give students the messy reality from day one?