Titration Calculator — Find Unknown Concentration
Calculate the unknown concentration in any acid-base titration from the volume and concentration of the titrant. Includes worked steps for exam technique.
Titration Technique and Calculations Guide
The Four-Step Titration Calculation
Always follow these steps: Step 1: moles of titrant = concentration × volume (in litres). Step 2: moles of analyte = moles of titrant × (ratio from equation). Step 3: concentration of analyte = moles ÷ volume of analyte (litres). Step 4: check units and significant figures. Example: 23.45 mL of 0.100 mol/L NaOH neutralises 25.00 mL HCl. Moles NaOH = 0.100 × 0.02345 = 0.002345 mol. Ratio 1:1, so moles HCl = 0.002345 mol. Concentration HCl = 0.002345 ÷ 0.025 = 0.0938 mol/L.
Titration Technique for Accurate Results
Rinse burette with titrant solution (not water) before filling — water dilutes the solution and changes concentration. Rinse pipette with analyte before use. Fill burette to a known level (not necessarily 0.00 mL) — read to 2 decimal places. Add indicator appropriate to the titration (phenolphthalein for weak acid/strong base; methyl orange for strong acid/weak base). Add titrant dropwise near the endpoint. Record the rough titre, then repeat two or more concordant titres (within 0.10 mL of each
Concordant Titres and Significant Figures
A concordant titre means two or more titration results agree to within 0.10 mL. If rough titre is 23.80 mL and repeats are 23.45 mL and 23.48 mL — use the mean of the two concordant results: (23.45 + 23.48)/2 = 23.465 → record as 23.47 mL. Never include the rough titre in the mean. Significant figures: titre readings to 2 decimal places (0.01 mL precision). Concentration answers to 3 significant figures unless data warrants otherwise. Volume in mL must be converted to litres (÷ 1000) before calc
Common Titration Pairs
Acid-base: HCl + NaOH (1:1 ratio, any indicator), H₂SO₄ + NaOH (1:2 ratio), HCl + Na₂CO₃ (2:1 ratio). Redox: KMnO₄ (purple) + Fe²⁺ in H₂SO₄ (1:5 ratio, KMnO₄ is self-indicating — turns from purple to colourless then pink at endpoint). Iodine + sodium thiosulfate (1:2 ratio, starch indicator turns blue-black then colourless at endpoint). Complexometric: EDTA with metal ions — used in water hardness determination. Back titration: add excess standard reagent, then titrate the excess — used when the
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