Titration of unknowns – vinegar, juice and hydrogen peroxide
ChemistryAcids, Bases & TitrationAges 17–18
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Sign in to playEvery run hides a randomly chosen concentration in a sample of hydrochloric acid, vinegar, fruit juice or pharmacy hydrogen peroxide. Titrate with standard NaOH and phenolphthalein or with acidified KMnO₄ (self-indicating), read the burette to 0.05 cm³ in the zoomed view, and do a rough titre followed by accurate titres until two are concordant. Work out the concentration (mol/dm³, g/dm³ or %) and check it: the simulation gives your percentage error and a full worked solution.
Lesson: Acid–base and redox (permanganate) titrations
What it shows
In a real lab the answer is never printed on the bottle. This simulation hides the concentration of each sample and asks students to find it with proper technique: reading a burette meniscus to 0.05 cm³, a rough titre, then accurate titres added drop by drop until two agree within 0.10 cm³. Hydrochloric acid and vinegar react 1 : 1 with sodium hydroxide, citric acid in fruit juice needs 3 mol NaOH per mole, and hydrogen peroxide reacts with permanganate in a 5 : 2 ratio. Flask colours are calculated from the real pH or from excess permanganate.
How to use
Choose a Sample and a Dilution, then read the Initial reading in the zoomed burette view. Press Open fully for a rough titre, close the tap, read the Final reading and press Record. For each accurate titre press Take sample, open the tap until about 1 cm³ before the rough value, then use +1 drop until the colour stays. Enter your answer and press Check.
Parameters you can change
- Sample to analyse Hydrochloric acid of unknown concentration, Vinegar (CH₃COOH), Fruit juice (citric acid, triprotic), Pharmacy H₂O₂ (titrated with KMnO₄)
- Sample dilution Recommended for each sample, Undiluted, ×2 (50.00 cm³ → 100.0 cm³), ×5 (50.00 cm³ → 250.0 cm³), ×10 (25.00 cm³ → 250.0 cm³), ×25 (10.00 cm³ → 250.0 cm³)
- Read the burette automatically
Questions to explore
- Why does citric acid in fruit juice need three times as many moles of NaOH as moles of acid?
- Why is no indicator added in a permanganate titration, and why is its burette read at the top of the meniscus?
- Why would undiluted vinegar be a poor choice for a titration with a 50 cm³ burette?
