Titration experiment: titrant, titrate and virtual labs
A titration finds the unknown concentration of a solution by adding a solution of known concentration from a burette until the reaction is just complete. Learn the words and practise 13 titrations as 3D virtual labs: acid–base, redox, precipitation and more.
Titrant and titrate: what do they mean?
The titrant is the solution of known concentration. It is poured from the burette. The solution being measured (also called the analyte, or the titrate) is in the conical flask. “To titrate” means to add the titrant slowly to the flask.
The end point is the moment the indicator changes colour. It should be as close as possible to the equivalence point, where the two reactants have reacted in exactly the amounts in the balanced equation.
How an acid–base titration works
Pipette a fixed volume of the unknown solution into a conical flask and add two drops of indicator, for example phenolphthalein for a strong base titrated with a strong acid. Fill the burette with the titrant, note the first reading, and run it in slowly while swirling. Stop at the first permanent colour change and note the final reading.
Repeat until two readings agree (concordant readings). Then use M₁V₁ = M₂V₂ for a 1:1 reaction, or the mole ratio of the balanced equation, to find the unknown concentration.
Other kinds of titration
In a redox titration, such as potassium permanganate against oxalic acid or Mohr’s salt, the colour of the permanganate itself shows the end point. A back titration measures an excess. Conductometric and thermometric titrations follow the end point by a change in conductivity or temperature instead of an indicator.
Virtual labs: titration (13)
- Acid–base titration with phenolphthalein Class 11 · freeFind the volume of 0.1 M NaOH that exactly neutralises 20 mL of 0.1 M HCl.
- Double-indicator titration of sodium carbonate Class 11Titrate Na₂CO₃ with HCl and observe two end points — CO₃²⁻ → HCO₃⁻ and HCO₃⁻ → CO₂.
- Precipitation titration: Mohr's method for chloride Class 11Find the concentration of chloride by titrating with silver nitrate using potassium chromate as indicator.
- Titration of acetic acid with NaOH Class 11Titrate 0.1 M acetic acid with 0.1 M NaOH using phenolphthalein and see why the end point is basic.
- Iodometric titration of copper(II) Class 11Liberate iodine from KI with Cu²⁺ and titrate it with sodium thiosulphate using starch.
- Redox titration: KMnO₄ vs Mohr's salt Class 11Determine the volume of 0.01 M KMnO₄ needed to oxidise Fe²⁺ in 20 mL of 0.05 M Mohr's salt.
- Redox titration: KMnO₄ vs oxalic acid Class 11Titrate warm acidified oxalic acid with KMnO₄ and find its concentration.
- Methyl orange for a strong acid–strong base titration Class 11Titrate 20 mL of 0.1 M HCl with 0.1 M NaOH using methyl orange and show it gives the same titre as phenolphthalein.
- Purity of marble: back titration with NaOH Class 11Find the mass of CaCO₃ in a marble sample by dissolving it in a known excess of HCl and titrating the leftover acid with NaOH.
- Thermometric titration: HCl and NaOH, the temperature peaks at the end point Class 11Add 1 M NaOH in portions to 50 mL of 1 M HCl and watch the temperature rise to a maximum at 50 mL, then fall.
- Titrating a dibasic acid: H₂SO₄ with NaOH Class 11Find the volume of 0.1 M NaOH needed to neutralise 20 mL of 0.1 M H₂SO₄ and see why it is twice the volume needed for HCl.
- Conductometric titration: HCl with NaOH (V-shaped curve) Class 12Add 0.1 M NaOH to 50 mL of 0.1 M HCl in portions, measuring the conductivity each time, and locate the end point at the minimum.
- Conductometric titration: acetic acid with NaOH Class 12Add 0.1 M NaOH to 50 mL of 0.1 M acetic acid in portions and show that the conductivity rises, with a sharper rise after the end point.
Frequently asked questions
What is a titrant?
The titrant is the solution of known concentration that is added from the burette during a titration.
What is the difference between end point and equivalence point?
The equivalence point is where the reactants have reacted exactly in the ratio of the balanced equation. The end point is where the indicator changes colour. A good indicator makes them almost the same.
Which indicator is used in an acid–base titration?
Phenolphthalein for a strong base titrated against a strong or weak acid, and methyl orange when the acid is strong and the base is weak. The choice depends on the pH at the equivalence point.
Can I do the titration experiment online?
Yes. In the virtual lab you fill the burette, add the indicator and run the titrant drop by drop, then read the volume. A number of labs are free.
More: Class 11 Chemistry practicals · Class 12 Chemistry practicals · Salt analysis