Sulphuric Acid Reactions (school)

Dilute H₂SO₄: typical acid reactions (H⁺ chemistry) — neutralises bases/oxides, reacts with carbonates releasing CO₂, reacts with reactive metals releasing H₂. Examples: NaOH → sodium sulphate + water CuO → copper sulphate + water CaCO₃ → calcium sulphate + CO₂ + water Zn → zinc sulphate + H₂ Concentrated H₂SO₄: dehydrating / oxidising behaviour emphasised in school (not the same as dilute acid reactions).

Treat dilute sulphuric acid first as a strong diprotic acid in aqueous solution. It neutralises sodium hydroxide to sodium sulphate and water. It reacts with copper(II) oxide to copper sulphate and water. Carbonates such as calcium carbonate give a sulphate salt, carbon dioxide, and water — the CO₂ test (limewater) is a classic observation link. Zinc and other reactive metals liberate hydrogen gas with dilute acid, forming the metal sulphate. Concentrated sulphuric acid is a different exam character: highly dehydrating and, toward some substances, oxidising. Do not write dilute-acid hydrogen displacement equations and claim they are “concentrated H₂SO₄ behaviour” without care. Always name the salt as a sulphate and balance for H₂SO₄ providing two H⁺ when needed in ionic thinking.

Dilute H₂SO₄ behaves like a typical acid. It reacts with NaOH, CuO, CaCO₃, and Zn in the usual school ways. Products are sulphate salts; metals like Zn give hydrogen gas. Concentrated H₂SO₄ is harsher — dehydrating/oxidising — not the same story as dilute.

Write word or symbol equations: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O H₂SO₄ + CuO → CuSO₄ + H₂O H₂SO₄ + CaCO₃ → CaSO₄ + CO₂ + H₂O H₂SO₄ + Zn → ZnSO₄ + H₂ State observations where relevant (CO₂ with carbonate; H₂ with Zn). Separate dilute vs concentrated uses in sentences.

H₂SO₄ is diprotic: full neutralisation of NaOH needs a 1:2 acid:alkali mole ratio for Na₂SO₄. Incomplete neutralisation can give NaHSO₄ (hydrogen sulphate) if stoichiometry is limited — mention only if the syllabus asks. Concentrated acid’s dehydrating action on sugar/formic acid type demos is a separate strand from the dilute reaction set with NaOH, CuO, CaCO₃, and Zn.

Dilute H₂SO₄: NaOH / CuO / CaCO₃ / Zn → sulphate products · CaCO₃ gives CO₂ · Zn gives H₂ · Conc. ≠ dilute behaviour.