Edexcel iGCSE Chemistry -2.43C Practical: Lead(II) Sulfate- Study Notes- New Syllabus

Edexcel iGCSE Chemistry -2.43C Practical: Lead(II) Sulfate- Study Notes- New syllabus

Edexcel iGCSE Chemistry -2.43C Practical: Lead(II) Sulfate- Study Notes -Edexcel iGCSE Chemistry – per latest Syllabus.

Key Concepts:

2.43C practical: prepare a sample of pure, dry lead(II) sulfate

Edexcel iGCSE Chemistry -Concise Summary Notes- All Topics

2.43C Practical: Preparation of Pure, Dry Lead(II) Sulfate

Lead(II) sulfate, \( \mathrm{PbSO_4} \), is an insoluble salt.

It is prepared using a precipitation reaction between two soluble salts.

Principle of the Reaction

A soluble lead(II) salt is reacted with a soluble sulfate salt.

Example:

\( \mathrm{Pb(NO_3)_2(aq) + Na_2SO_4(aq) \rightarrow PbSO_4(s) + 2NaNO_3(aq)} \)

The ionic equation is:

\( \mathrm{Pb^{2+}(aq) + SO_4^{2-}(aq) \rightarrow PbSO_4(s)} \)

Lead(II) sulfate forms as a white precipitate.

Apparatus

  • Beakers
  • Measuring cylinder
  • Glass stirring rod
  • Filter funnel and filter paper
  • Distilled water
  • Drying oven or filter paper

Method

  • Measure a known volume of lead(II) nitrate solution into a beaker.
  • Add sodium sulfate solution slowly while stirring.
  • A white precipitate of lead(II) sulfate forms.
  • Allow the precipitate to settle.
  • Filter the mixture to collect the solid.
  • Wash the precipitate with distilled water to remove soluble impurities (e.g. sodium nitrate).
  • Dry the solid in a warm oven or between filter papers.

Observations

  • Clear colourless solutions before mixing.
  • White precipitate forms immediately.
  • Solid remains on filter paper after filtration.

Why Washing Is Necessary

  • The filtrate contains soluble sodium nitrate.
  • Washing removes these impurities.
  • This ensures the final solid is pure lead(II) sulfate.

Safety Considerations

  • Lead compounds are toxic.
  • Wear gloves and avoid ingestion.
  • Dispose of waste properly.
StagePurpose
Mix solutionsForm precipitate
FiltrationSeparate solid
WashingRemove soluble impurities
DryingObtain pure dry sample

Example 1 (Conceptual):

Why can lead(II) sulfate be prepared by precipitation?

▶️ Answer/Explanation

Because lead(II) sulfate is insoluble in water.

It forms a solid when two soluble salts are mixed.

Example 2 (Application):

What would happen if the precipitate was not washed?

▶️ Answer/Explanation

Soluble impurities (e.g. sodium nitrate) would remain.

The final product would not be pure.

Example 3 (Hard):

Explain fully how this method ensures a pure, dry sample of lead(II) sulfate is obtained.

▶️ Answer/Explanation

Two soluble salts are reacted to form an insoluble precipitate of \( \mathrm{PbSO_4} \).

Filtration separates the solid from the solution.

Washing removes soluble by-products such as \( \mathrm{NaNO_3} \).

Drying removes water from the surface.

Therefore only pure, dry lead(II) sulfate remains.

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