What is Titration?

Titration is a laboratory method to determine the concentration or volume of an acid or alkali by reacting it with a solution of known concentration.

It is based on the idea of neutralisation:

Acid + Base → Salt + Water

Example:

H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O

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1. Key Definitions

Term	Meaning
Titration	Method to find an unknown concentration using neutralisation
Titre	Volume delivered from the burette
End-point	Point where indicator changes colour
Concordant results	Titres close to each other (usually within 0.10–0.20 cm³)
Standard solution	Solution with known concentration
Neutralisation	Acid reacts with alkali to form salt + water

SEAB commonly expects burette readings to the nearest 0.05 cm³ and concordant titres within about 0.20 cm³. 

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2. Apparatus and Their Functions

(a) Burette

• Holds the solution added during titration
• Usually 50.0 cm³
• Used for variable volumes
• Read to 2 decimal places
• Precision: nearest 0.05 cm³

Important:

• Scale goes from top to bottom
• 0 cm³ at the top
• 50 cm³ at the bottom

Common mistakes

❌ Reading from top incorrectly
❌ Not removing air bubbles
❌ Reading meniscus wrongly

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(b) Pipette

• Measures a fixed volume
• Usually 25.0 cm³
• More accurate than measuring cylinder

Important:

• Use a pipette filler
• Never suck by mouth

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(c) Conical Flask

• Contains solution being analysed
• Easy to swirl without spilling

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(d) White Tile

• Helps observe colour change clearly

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(e) Indicator

• Substance that changes colour near end-point

Common indicators:

• Methyl orange
• Phenolphthalein

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3. Indicator Colours

Methyl Orange

In Acid	Neutral	In Alkali
Red	Orange	Yellow

Typical colour change in titration

• Alkali → acid added:
  • Yellow → orange

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Phenolphthalein

In Acid	In Alkali
Colourless	Pink

Typical colour change

• Alkali → acid added:
  • Pink → colourless

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4. Choosing the Correct Indicator

For O-Level:

• Strong acid + strong alkali:
  • Either methyl orange or phenolphthalein works

Examiner favourites

• Methyl orange often used in school practicals
• Phenolphthalein sometimes tested

Wide-range indicators are unsuitable because colour change is not sharp enough.

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5. Step-by-Step Titration Procedure

Step 1 — Rinse apparatus

Burette

• Rinse with distilled water
• Then rinse with solution going inside

Pipette

• Rinse with solution to be pipetted

Conical flask

• Rinse with distilled water only

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Step 2 — Fill burette

• Use funnel
• Remove funnel afterwards
• Ensure no air bubbles
• Record initial reading

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Step 3 — Pipette solution

• Pipette exactly 25.0 cm³
• Transfer into conical flask

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Step 4 — Add indicator

• Add 2–3 drops only

Too much indicator causes error.

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Step 5 — Perform rough titration

• Add solution quickly while swirling
• Stop when colour changes

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Step 6 — Accurate titration

Near end-point:

• Add solution drop by drop
• Swirl continuously

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Step 7 — Record final reading

Calculate:

Titre = Final burette reading – Initial burette reading

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Step 8 — Repeat

Repeat until:

• Two titres are concordant

Typical acceptable difference:

• ≤ 0.10 cm³
• Sometimes ≤ 0.20 cm³ in practical guidance 

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6. How to Read the Burette Correctly

Read at eye level

To avoid:

• Parallax error

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Read bottom of meniscus

For colourless solutions:

• Read lowest point of curve

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Record to 2 decimal places

Correct:

• 24.50 cm³
• 18.05 cm³

Wrong:

• 24.5
• 18.053

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7. Concordant Results

Meaning

Titres close together.

Example:

Trial	Titre/cm³
1	24.80
2	24.75
3	24.85

Trials 2 and 3 are concordant.

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Average titre

Use only concordant values.

Example:

Average titre = 24.75 + 24.852

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8. Titration Calculations

This is the MOST tested section.

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Step-by-Step Calculation Method

Step 1 — Write balanced equation

Example:

H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O

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Step 2 — Convert volume to dm³

1 dm³ = 1000 cm³

Example:

25.0 cm³ = 0.0250 dm³

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Step 3 — Use mole formula

n = cV

Where:

• n = moles
• c = concentration
• V = volume in dm³

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Step 4 — Use mole ratio

From balanced equation.

Example:

• 1 mol H₂SO₄ reacts with 2 mol NaOH

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Step 5 — Find unknown concentration

Rearrange:

c = nv

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9. Worked Example

Question

25.0 cm³ of sodium hydroxide reacted with 20.0 cm³ of 0.100 mol/dm³ sulfuric acid.

Find concentration of sodium hydroxide.

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Step 1

Balanced equation:

H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O

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Step 2

Moles of sulfuric acid:

n = cV = 0.100 x 0.0200

= 0.00200 mol

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Step 3

Use ratio:

1:2

NaOH moles:

= 0.00400 mol

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Step 4

Volume of NaOH:

25.0 cm³ = 0.0250 dm³

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Step 5

Concentration:

c =0.004000.0250

= 0.160 mol/dm³

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10. Sources of Error

Error	Effect
Overshooting end-point	Titre too large
Air bubble in burette	Wrong titre
Parallax error	Wrong reading
Not rinsing apparatus properly	Dilution error
Adding too much indicator	Affects result

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11. Improvements

Problem	Improvement
Difficult to see colour	Use white tile
Overshooting	Add dropwise near end-point
Human judgement error	Repeat titrations
Parallax	Read at eye level

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12. Practical Exam Tips

Before starting

✔ Check burette for air bubbles
✔ Remove funnel
✔ Record initial reading properly

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During titration

✔ Swirl continuously
✔ Wash flask walls with distilled water
✔ Slow down near end-point

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Near end-point

✔ Add one drop at a time
✔ Watch carefully for permanent colour change

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13. Colour Change Tips

Methyl orange

• Yellow → orange = end-point
• Red means overshot

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Phenolphthalein

• Pink → colourless = end-point

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14. Common Exam Questions

Describe how to carry out a titration

Must mention:

• Pipette 25.0 cm³ into flask
• Add indicator
• Fill burette
• Record readings
• Add solution slowly with swirling
• End-point colour change
• Repeat for concordant results

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Why use conical flask?

Allows swirling without spilling.

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Why use pipette instead of measuring cylinder?

More accurate.

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Why remove funnel?

Drops may enter burette and change reading.

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Why wash flask sides with distilled water?

Ensures all reactants react.

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15. Must-Memorise Values

Item	Value
Pipette reading	1 d.p.
Burette reading	2 d.p.
Burette precision	0.05 cm³
Concordant titres	within 0.10–0.20 cm³
Pipette common volume	25.0 cm³
Burette common volume	50.0 cm³

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16. Ultimate Exam Checklist

Before practical ends:

✅ Initial and final readings recorded
✅ 2 decimal places used
✅ Concordant results obtained
✅ Average titre calculated correctly
✅ Units included
✅ Balanced equation written
✅ Mole ratio used correctly
✅ Volume converted to dm³

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17. High-Yield Mistakes Students Make

❌ Forgetting to convert cm³ to dm³
❌ Using wrong mole ratio
❌ Reading top of meniscus
❌ Overshooting endpoint
❌ Averaging rough titre with accurate titres
❌ Forgetting units
❌ Recording burette reading with 1 d.p.

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18. Fast Memory Summary

TITRATION FORMULA FLOW

Volume → dm³ → n = cV → mole ratio → c = nv

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19. What Cambridge Examiners Look For

• Accurate technique
• Proper burette readings
• Correct significant figures
• Concordant titres
• Proper mole calculations
• Clear practical method

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