Based on the provided reference, while the colour "white" is commonly associated with solid salts containing certain ions, the ions themselves are typically colourless when dissolved in aqueous solution. The reference details the colour of salts (ionic compounds) in their solid state and when dissolved in water.
Colour of Salts Containing Specific Ions
The reference indicates that the solid forms of salts containing the following ions are white:
- Metal Cations: Sodium (Na⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺), Aluminium (Al³⁺), Zinc (Zn²⁺), Lead (Pb²⁺), Ammonium (NH₄⁺)
- Anions: Chloride (Cl⁻), Sulphate (SO₄²⁻), Nitrate (NO₃⁻), Carbonate (CO₃²⁻)
It is important to note that in an aqueous solution, the salts of these ions are described as colourless in the reference. The perceived colour of a solid ionic compound arises from its interaction with light, which is influenced by the crystal structure and the electronic properties of the constituent ions, rather than being an intrinsic property of the isolated ion itself.
The table below summarizes the information from the reference regarding the colour of salts containing these ions:
| Salt or Metal Oxide Type | Solid Colour | Aqueous Solution Colour |
|---|---|---|
| Salt of Sodium, Calcium, Magnesium, Aluminium, Zinc, Lead, Ammonium | White | Colourless |
| Salt of Chloride, Sulphate, Nitrate, Carbonate | White | Colourless |
Therefore, while many common salts containing ions like Na⁺, Ca²⁺, Mg²⁺, Al³⁺, Zn²⁺, Pb²⁺, NH₄⁺, Cl⁻, SO₄²⁻, NO₃⁻, and CO₃²⁻ are white in their solid state, the ions themselves are typically colourless when hydrated in water.
