neutralization reaction

Meaning: An acid and a base react to give a salt and, for Arrhenius species, water. For a strong acid and strong base the net ionic equation is H⁺ + OH⁻ → H₂O, and the spectator ions make up the salt. The final pH depends on whether the salt's ions hydrolyze. Strong acid with strong base gives pH 7 at 25 °C. Weak acid with strong base gives pH above 7, because the conjugate base accepts H⁺ from water. Weak base with strong acid gives pH below 7, because the conjugate acid donates H⁺.

Equation: MaVa = MbVb at equivalence for a monoprotic acid and a monoprotic base, where M is molarity (mol/L) and V is volume (L). For polyprotic acids or bases, multiply each side by the number of H⁺ or OH⁻ per formula unit.

On the MCAT: Passages use titrations. You find the equivalence point on a curve, calculate an unknown concentration, predict the pH at equivalence, or pick a suitable indicator. For a weak acid titrated with strong base, pH = pKa at the half-equivalence point. If the amounts are not matched, find which reagent is in excess and use the leftover moles to get the pH.

Common confusion: Students equate neutralization with pH 7. The settling fact is that the equivalence-point pH is set by the salt. Acetic acid plus NaOH gives sodium acetate, and the solution is basic.