Acid-base chemistry, pH and neutralisation

≈ 50 min

Acid-base chemistry, pH and neutralisation

Acids and bases are described by their behaviour in water. A strong acid ionises extensively; a weak acid ionises only partially. Strength is not the same as concentration: a dilute strong acid can have lower hydrogen-ion concentration than a concentrated weak acid. pH is a logarithmic measure of hydrogen-ion concentration, pH = −log[H⁺], so a one-unit pH change represents a tenfold change in [H⁺]. Neutralisation involves H⁺ and OH⁻ forming water. Use formula, ionic and net ionic representations carefully, then connect a pH or indicator observation to the chemical system.

Work it through

For [H⁺] = 1.0 × 10⁻³ mol dm⁻³, pH = 3.0. If a strong acid is diluted tenfold, [H⁺] becomes one tenth and pH rises by one unit. This does not make it a weak acid; strength refers to ionisation extent, not the amount of acid originally added.

Mastery target

Distinguish acid strength from concentration, calculate or interpret pH and represent a simple neutralisation with correct ions and conditions.

What is the pH of a solution with [H⁺] = 1.0 × 10⁻³ mol dm⁻³?

−3

0.003

Name the key chemistry term from Acid-base chemistry, pH and neutralisation that best fits the explanation and visual model.

Calculate the pH for [H⁺] = 1.0 × 10⁻² mol dm⁻³.

Which statement corrects a common misunderstanding in Acid-base chemistry, pH and neutralisation?

Correct: Strong versus weak describes extent of ionisation; concentrated versus dilute describes amount per volume. They are separate ideas.

A chemical equation can be interpreted without conditions, states, charges or conserved quantities.

A calculation is correct whenever its final number is familiar, even if the units are inconsistent.

A single observation proves a mechanism without alternative explanations or evidence.