Preparing an Insoluble Salt (Edexcel GCSE Combined Science): Revision Note

Preparing an Insoluble Salt

Aim:

To prepare a dry sample of an insoluble salt, lead(II) sulfate

Diagram:

The preparation of lead(II)sulfate by precipitation from two soluble salts

Method:

• Measure out 25 cm³ of 0.5 mol dm³ lead(II) nitrate solution and add it to a small beaker

• Measure out 25 cm³ of 0.5 mol dm³ of potassium sulfate add it to the beaker and mix together using a stirring rod

• Filter to remove the precipitate from mixture

• Wash the filtrate with distilled water to remove traces of other solutions

• Leave in an oven to dry

 Soluble salt 1 = lead(II) nitrate Soluble salt 2 = potassium sulfate

Equation for the reaction: 

Pb(NO₃)₂  (aq) + K₂SO₄ (aq) → PbSO₄ (s) + 2KNO₃ (aq)

lead(II) nitrate + potassium sulfate → lead(II) sulfate + potassium nitrate