Question: is mg soluble in water?
Answer: In seawater it can also be found as MgSO4. Water solubility of magnesium hydroxide is 12 mg/L. Other magnesium compounds are clearly more water soluble, for example magnesium carbonate (600 mg/L). Magnesium sulphate adds a bitter flavour to water, and has a water solubility of 309 g/L at 10oC.