Expert: George Maxwell - 7/13/2007

Question
Experience teaches us that most solids are more soluble in warm water than in cold water. Does the solubility of Mg(OH)2 (magnesium hydroxide) fit this pattern?

Answer
Hi, and thank you for your question.

As far as I know, the "solubility of solids rule" (e.g. more soluble with increasing temperature) applies to magnesium hydroxide.

However, Mg(OH)2 is almost insoluble in water (0.0012 g is the maximum amount that can be dissolved in 100 g water at room temperature). The solubility is so small, and increases so slowly with temperature, that you are unlikely to be able to measure it accurately without specialist equipment, so your results may seem to show that temperature does not affect the solubility of magnesium hydroxide.
Hope this helps, and thanks again for your question.