Titration Station
Use a burette, choose an indicator and calculate an unknown acid concentration.
Burette and conical flask
Concept figure: neutralisation
A monoprotic acid needs one mole of NaOH per mole of acid for complete neutralisation.
Perform the titration
Coarse: 1.00 cm³. Fine: 0.05 cm³. Adjust the stopcock to approach the end point.
Live titration curve
The yellow marker shows your current volume. The equivalence point will be marked after Check.
The chemistry
Strong acid: HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l).
Weak acid: CH₃COOH(aq) + NaOH(aq) → CH₃COONa(aq) + H₂O(l).
Stoichiometry: c(acid) × V(acid) = c(NaOH) × V(equivalence), with both volumes in the same units, for monoprotic acids.
At 25 °C: Kᵥ = Kᵥ is not used; the water ion product is Kᵥ-independent and written Kw = 1.0 × 10⁻¹⁴ mol²/dm⁶. For ethanoic acid, Ka = 1.8 × 10⁻⁵ mol/dm³.
Phenolphthalein changes from colourless to pink around pH 8.2–10.0. Methyl orange changes from red to yellow around pH 3.1–4.4. A weak acid–strong base titration requires an indicator whose transition occurs within its alkaline pH jump.
The pH curves assume ideal dilute aqueous solutions at 25 °C with additive volumes and complete NaOH dissociation. Indicator colours are approximated.