Question

1. Why is Plaster of Paris stored in a moisture proof container?

Answer 1

Answer:

Calcium sulfate CaSO4 is commonly known as plaster of Paris. It is a semihydrate substance because of half molecule of H2O attached to it. If it comes into contact with water or moisture accidentally then it becomes a solid hard substance.

When calcium sulfate is mixed with water, two molecules of water are added to it and is converted into gypsum crystal with chemical formula CaSO4.2H2O.

Hence, it becomes useless therefore it should be kept in places free of moisture.

Answer 2

Answer:

Plaster of Paris in contact with moisture (water) changes to solid hard mass, gypsum. Therefore, it gets wasted. Hence it should be stored in moisture proof containers.