Preparing Insoluble Salts by Precipitation

Preparing Insoluble Salts by Precipitation

Precipitation in Chemistry

• Precipitation is the formation of a solid (the precipitate) upon mixing two solutions.
• One solution must contain the positive ions in the insoluble precipitate, and the other must contain the negative ions.

Solubility Rules

Soluble

• ALL sodium, potassium, and ammonium salts.
• ALL nitrates.
• Halides (except $Ag$ and $Pb$).
• Sulphates (except $Ca$, $Ba$, and $Pb$).

Insoluble

• Carbonates (except $K$, $Na$, and $NH_4{^+}$).

Quick Test

• Determine the metal ion present in a given precipitate.

Suggest Starting Compounds For:

• Lead sulphate
• Calcium carbonate
• Silver bromide
• Barium sulphate
• Lead iodide

Practical Task

• Use the provided apparatus to prepare a sample of lead iodide.
• Have the method checked by the teacher before starting.