Reactions & Equilibrium · Chemistry

Titration Virtual Lab 3D: Burette, Indicators, pH Curve

A 3D titration bench where every piece of apparatus is real and explains itself: hover over (or tap) the burette, stopcock, clamp, conical flask, white tile, pipette, filler, wash bottle or indicator to learn what it is for. Open the tap drop by drop or as a stream, swirl the flask, and watch each drop's pocket of pink fade more slowly as the end point nears; a lens shows the burette's 0.1 mL markings at the meniscus, and Inside the flask shows the ions meeting and the indicator molecules changing form. Ten modules: the apparatus, reading a burette (meniscus and parallax), a first HCl–NaOH titration with unknowns, the pH curve and its jump, how an indicator works, choosing an indicator, a weak acid's buffer region, sodium carbonate's two end points, KMnO₄ as a self-indicator (warming oxalic acid, autocatalysis), and the classic mistakes.

Interactive virtual lab · no download · works on phones and laptops

Chapter: Titration & Volumetric Analysis
For: Class 10–12 · JEE · NEET
Time: ~45 min

Titration Lab (3D): Acid–Base & KMnO₄ is a Pro simulation

Pro opens all 163 virtual labs — 810 simulations with guides and quizzes.

How to use it

1Pick a module (10, in five groups); set your level at the top right.
2Hover over or tap any apparatus to learn about it. Tap the stopcock chip to cycle Closed → Drop by drop → Stream, '+ 1 drop' for a single drop, and the flask (or Swirl) to swirl. 'Refill · new flask' starts a fresh run.
3Save each run with Compare to collect concordant readings; watch Inside the flask and the pH curve under the bench.
4Use Predict before you look, then Derive, Questions and Practise.

What to notice

A burette reads $0$ at the top and $50$ at the bottom; least count $0.1 mL$ , read to $0.05 mL$ at the bottom of the meniscus (top for KMnO₄), eye level.
Near the end point each drop's colour lingers longer: slow to single drops and swirl.
At the end point $M_{1} V_{1} n_{1} = M_{2} V_{2} n_{2}$ ; use two concordant titres (within $0.1 mL$ ).
An indicator changes over about $p K_{I n} \pm 1$ and must change inside the curve's jump: phenolphthalein for weak acids, methyl orange for weak bases.
At half-equivalence of a weak acid, $pH = p K_{a}$ ; Na₂CO₃ with HCl shows two end points, the second at twice the first.
KMnO₄ is its own indicator; oxalic acid is warmed to 60–70 °C and the Mn²⁺ formed speeds the reaction up.

For teachers

A ready-made teaching kit comes with this lab

Lesson plan
41 min, 4 steps
Ask the class
4 questions with answers
Quick quiz
7 questions, printable
Key formulas
6 formulas

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About the Titration Lab (3D): Acid–Base & KMnO₄ simulation

This titration virtual lab puts a full volumetric-analysis bench in 3D: a 50 mL burette held in a clamp stand, a conical flask on a white tile, a volumetric pipette with its filler, a wash bottle, an indicator bottle and a volumetric flask. Hover over any piece (or tap it on a phone) and it tells you what it is for and how it is used — which apparatus is rinsed with the solution and which with water, why the funnel comes off before reading, why the pipette's last drop is never blown out. The burette is engraved every 0.1 mL from 0 at the top to 50 at the bottom, and a lens beside it shows the meniscus on the scale exactly as you would read it.

Run a titration the way it is done in the Class 11–12 practical. A hand turns the stopcock — closed, drop by drop, or a stream — and another hand swirls the flask. Each drop makes a pocket of colour that fades as it mixes: quickly while plenty of acid is left, more and more slowly as the end point nears, and faster when you swirl. Stop at the first faint pink that lasts, save the run, refill and repeat until two titres agree within 0.1 mL. Inside the flask shows the same titration as particles: OH⁻ ions arriving with each drop, meeting H₃O⁺ to make water, Na⁺ and Cl⁻ looking on, and the indicator's HIn and In⁻ forms changing over.

Ten modules cover the syllabus: the apparatus; reading a burette (meniscus and parallax); a first HCl–NaOH titration with unknown acids; the pH curve and its jump, drawn live by a pH meter; how an indicator works (HIn ⇌ H⁺ + In⁻, a range of about pK ± 1); choosing the right indicator for strong and weak acids and bases; a weak acid's buffer region and pH = pKa at half-equivalence; sodium carbonate's two end points with phenolphthalein and methyl orange; potassium permanganate as a self-indicator against oxalic acid and Mohr's salt, with warming and autocatalysis; and the classic mistakes and which way each pushes the answer. The pH everywhere is solved from the full charge balance, not from shortcut formulas.

Also covers: titration, titration virtual lab, titration simulation, acid base titration, burette, how to read a burette, burette least count, meniscus reading, parallax error burette, pipette, conical flask, white tile titration, titration apparatus, end point, equivalence point, phenolphthalein, methyl orange, methyl red, bromothymol blue, choice of indicator, indicator range, theory of indicators, hin in- equilibrium, ph curve, titration curve, ph jump, hcl vs naoh, acetic acid vs naoh, weak acid strong base titration, half equivalence ph = pka, buffer region, ammonia vs hcl, sodium carbonate hcl two end points, double indicator titration, kmno4 titration, oxalic acid kmno4, mohr's salt titration, self indicator, autocatalysis mn2+, concordant readings, m1v1 = m2v2, normality titration, volumetric analysis, titration errors, class 11 chemistry lab experiment, class 12 chemistry lab experiment.

Frequently asked questions

How do you read a burette correctly?

Hold the eye level with the liquid surface and read the bottom of the curved meniscus for colourless solutions (the top for dark ones like KMnO₄). The scale reads 0 at the top and 50 at the bottom, marked every 0.1 mL, so a reading is written to the nearest 0.05 mL, for example 23.45 mL. Looking from above gives a reading that is too small, from below one that is too large — the parallax error.

Which indicator is used for which titration?

Strong acid with strong base: almost any (phenolphthalein, methyl red or methyl orange), because the pH jumps from about 3.5 to 10.5 in one drop. Weak acid with strong base (acetic acid with NaOH): phenolphthalein, since the equivalence pH is about 8.7. Weak base with strong acid (ammonia with HCl): methyl orange or methyl red, since the equivalence pH is about 5.3. Weak acid with weak base: no indicator gives a sharp end point.

Why is the burette rinsed with the titrant but the conical flask with water?

Any water left in the burette dilutes the titrant, so more of it is needed and the answer comes out too high; rinsing with the titrant leaves only titrant behind. The flask must contain exactly the moles the pipette delivers: water adds no moles, but a rinse with the solution would add extra.

Why is oxalic acid warmed before titrating with KMnO₄?

The reaction between permanganate and oxalic acid is slow at room temperature, so each drop's purple lingers and the end point is overrun. At 60–70 °C it is fast enough, and once some Mn²⁺ has formed it catalyses the reaction further (autocatalysis), so later drops decolourise almost at once. Above about 80 °C oxalic acid begins to decompose.