Neutralisation is the reaction between an acid and a base or alkali to produce a salt and water only; ionically it is H⁺ + OH⁻ → H₂O.
Malay: Peneutralan · Chinese: 中和
Neutralisation is the reaction between an acid and a base or alkali to produce a salt and water only. The words “salt and water only” carry the mark: no gas and no other product is formed when an acid meets a hydroxide or oxide. Stripped to its ions, every neutralisation is the same simple change, H⁺ + OH⁻ → H₂O, in which the hydrogen ion from the acid and the hydroxide ion from the alkali join to make water.
A worked example shows the full and ionic pictures. Hydrochloric acid with sodium hydroxide gives HCl + NaOH → NaCl + H₂O; the sodium and chloride ions are spectators, so the ionic equation is just H⁺ + OH⁻ → H₂O. The same holds for sulfuric acid with potassium hydroxide, or nitric acid with a metal oxide, always a salt plus water. Neutralisation is exothermic, so the mixture warms up as the reaction proceeds.
The confusion to avoid is with the acid–carbonate reaction, which also uses an acid but is not neutralisation in the strict sense, because it gives a salt, water and carbon dioxide. If a gas is released, the “salt and water only” definition is broken. A second slip is to assume the final solution is always exactly pH 7; with a strong acid and a weak alkali the end mixture can be slightly acidic, so “neutral” names the reaction type, not a fixed pH of exactly 7.
Within this chapter neutralisation is the reaction that titration measures and that one method of salt preparation relies on. Our teachers drill both the full equation and the H⁺ + OH⁻ → H₂O ionic form, since the exam can ask for either.
Want a teacher to make this click?
We teach SPM Chemistry one to one, so your child understands it and scores it.
from RM50/hr · One-hour paid trial · Same-day reply