What color precipitate do aluminium, calcium, and magnesium ions produce with sodium hydroxide solution?

When aluminium, calcium, and magnesium ions are treated with sodium hydroxide solution, they form precipitates that are all white in color. This is due to the formation of insoluble metal hydroxides.

Aluminium ions react with sodium hydroxide to form aluminium hydroxide, which is white and gelatinous. Calcium ions react to produce calcium hydroxide, which also appears as a white precipitate. Magnesium ions similarly react with sodium hydroxide to yield magnesium hydroxide, resulting in another white precipitate.

The key to understanding this is recognizing the nature of metal hydroxides formed in the presence of sodium hydroxide. Many metal ions form precipitates with hydroxide ions, and in this case, the specific ions mentioned produce a distinct white precipitate. Therefore, the identification of these ions based on the color of the precipitate assists in distinguishing between them in a laboratory context.