Why is magnesium sulfate a more effective drying agent than sodium sulfate?
Magnesium Sulfate: Magnesium sulfate is a great drying agent. It has a high capacity, is complete in its drying and is rapid. Capacity refers to how much water per gram the drying agent holds and complete means that drying equilibrium favors the hydrate. The only disadvantages to using magnesium sulfate is that it is normally available in a powder form and must be filtered out. More importantly, magnesium is a very strong Lewis acid and as such, is not inert to all functional groups. For example, epoxides are sensitive to magnesium. Sodium Sulfate: Sodium Sulfate is the most widely used drying agent. It is very similar to magnesium sulfate in its capacity, but it is less complete (will leave more water in solution) and it is slower in terms of its rate. Sodium sulfate has the advantage in that it is less reactive and in granular form, is very easy to remove from liquids. The liquid can often be decanted off the drying agent without filtration. Hope this helps!!
