12.2Experimental Techniques and Chemical Analysis

Acid-base titrations — Cambridge IGCSE Chemistry 0620 Revision Notes & Topical Questions

5 min read 11 parts Lesson 2 of 5 1 quiz

📚 Cambridge IGCSE Chemistry 0620 Hub / Topical Revision

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Lesson summary

12.2 Acid-base titrations — Notes — IGCSE Chemistry notes: Describe an acid-base titration using a burette, a volumetric pipette and a suitable indicator, and calculate concentrations.Titration — a method of analysing the concentration of a solutionUse — finds exactly how much al…

Volumetric pipette and filler
50 cm3 burette
250 cm3 conical flask
Small funnel
Indicator, clamp stand and white tile
Concordant results

Part 1 of 9Purpose of a titration

Titration

Titration a method of analysing the concentration of a solution

Use

Use finds exactly how much alkali neutralises a quantity of acid, and the reverse

Other use

Other use titrations can also be used to prepare salts

Part 2 of 9Apparatus

Apparatus

Volumetric pipette and filler

Volumetric pipette and filler measure exactly 25 cm³ of one solution

50 cm³ burette

50 cm³ burette delivers the other solution

250 cm³ conical flask

250 cm³ conical flask holds the solution to be titrated

Small funnel

Small funnel used to fill the burette

Indicator, clamp stand and white tile

Indicator, clamp stand and white tile show the colour change clearly

Part 3 of 9Acid-base titration method

Use a pipette and filler to place exactly 25 cm³ of one solution (e.g. sodium hydroxide) into a conical flask.

Fill the burette with the other solution (e.g. acid) using a small funnel, then remove the funnel.

Run a little solution through the jet so there are no air bubbles, then record the start reading to the nearest 0.05 cm³.

Stand the flask on a white tile under the burette and add a few drops of a suitable indicator.

Do a rough titration, running in 1-3 cm³ portions while swirling, and close the tap at the end-point.

Repeat with a fresh sample, adding drop by drop near the rough end-point until the indicator just changes colour.

Record the volume to the nearest 0.05 cm³ with the eye level with the bottom of the meniscus.

Repeat until two concordant results are obtained.

9End-point

End-point the point at which one drop causes a sharp colour change

10Concordant results

Concordant results titres within 0.1 cm³ of each other

11Titre

Titre final reading - first reading

12Uses

Uses finding the concentration of a solution and preparing salts

Rinse the pipette with the alkali and the burette with the acid, so that water does not dilute them.

Add the solution steadily while swirling, and find the mean of the concordant titres.

Part 4 of 9Indicators for titrations

Indicator	Colour in acid	Colour in alkali	Colour in neutral
Litmus solution	Red	Blue	Purple
Red litmus paper	Stays red	Turns blue	No change
Blue litmus paper	Turns red	Stays blue	No change
Methyl orange	Red	Yellow	Orange
Phenolphthalein	Colourless	Pink	Colourless
Thymolphthalein	Colourless	Blue	Colourless

Suitable indicators

Suitable indicators methyl orange and phenolphthalein give a sharp colour change at the end-point

Unsuitable

Unsuitable wide-range indicators such as litmus do not give a sharp change

End-point colours

End-point colours methyl orange is red in acid, yellow in alkali and orange at neutral, and phenolphthalein is colourless in acid and pink in alkali.

Universal indicator

Universal indicator it is unsuitable because it changes through many shades gradually.

Part 5 of 9Common titration errors

1Funnel left in the burette

Funnel left in the burette drips can add liquid and give false, high readings

2Jet space not filled

Jet space not filled the part of the burette below the tap must be filled

3Wrong reading

Wrong reading the burette scale has 0.0 cm³ at the top, and readings are taken from the bottom of the meniscus

4Overshooting the end-point

Overshooting the end-point add the solution drop by drop near the end and do a rough titration first.

5Wrong rinsing

Wrong rinsing rinse each piece of equipment with the solution it will hold.

6Too much indicator

Too much indicator indicators are weak acids or bases themselves.

Part 6 of 9Titration calculations

Work out the moles of the solution of known concentration: moles = concentration (mol/dm3) × volume (dm3).

Use the mole ratio from the balanced equation to find the moles of the other reactant.

Divide those moles by the volume of that solution (in dm3) to find its concentration.

Volume conversion

1 dm³ = 1000 cm³

Concentration

Concentration moles ÷ volume in dm3, in mol/dm3

Mole ratio

NaOH + HCl → NaCl + H₂O is 1:1, but H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O is 1:2.

Mass concentration

Mass concentration g/dm³ = mol/dm³ × Mr.

Part 7 of 9Recording results

Table

Table use columns for rough, trial 1, trial 2 and trial 3, with the first reading, final reading and titre.

Burette readings

Burette readings record them to the nearest 0.05 cm³.

Rough titre

Rough titre it is not included in the mean unless it is concordant.

Part 8 of 9Preparing a pure soluble salt by titration

Titrate with indicator and note the exact volume of acid needed.

Repeat the mixing without indicator in the same volumes.

Evaporate the solution until crystals start to form.

Cool, filter and dry the crystals.

Part 9 of 9More from the specification

1Acid-Base Titration Protocol

A volumetric pipette transfers an exact aliquot of alkaline solution into a conical flask;
- acid is delivered incrementally from a burette until an indicator signals the exact stoichiometric neutralisation equivalence point.

2Acid-Base Indicator Selection

Sharp colorimetric end-points require appropriate indicators: phenolphthalein shifts from pink in alkaline solutions to colourless in acid,
while methyl orange transitions from yellow in alkali to red-orange in acid.

3Determining Concordant Titres

Titrations are repeated until at least two concordant titres agreeing within 0.10 cm³ are obtained, ensuring anomalous initial rough estimates are excluded from mean titre calculation.

4Temperature

A measure of the average kinetic energy of the particles.

5Accurate

Close to the true value.

6Substance

A material with only one type of particle.

7Displacement

A reaction in which a more reactive element takes the place of a less reactive one in a compound.

8Downward displacement

Collecting gas in an inverted measuring cylinder full of water.

Key terms

Term	Meaning
Titration	Method for finding the volume of one solution that reacts exactly with another.
Burette	Apparatus delivering a measured variable volume.
Pipette	Apparatus measuring a fixed volume such as 25.0 cm³.
End-point	Indicator changes colour sharply.
Concordant results	Titres within 0.1 cm³.
Concentration	Moles ÷ volume in dm³, in mol/dm³.
Titre	the volume of solution added from the burette.
Mole ratio	the ratio of the moles in the balanced equation.

Avoid these mistakes

Leaving the funnel in the burette, which gives false high readings, or rinsing the burette with water only — rinse it with the acid it will contain

Reading the burette from the top of the meniscus or forgetting 0.0 is at the top

Using litmus or universal indicator — they do not give a sharp end-point

Averaging titres that are not concordant, or including the rough titre in the mean

Ignoring the mole ratio when the acid is sulfuric acid, or forgetting to convert cm3 to dm3

Last updated: 18 October 2026