Which is the formula of plaster of Paris?
Answer and explanation
Correct answer: CaSO₄·½H₂O
Plaster of Paris is calcium sulphate hemihydrate. During its preparation, gypsum, CaSO₄·2H₂O, is heated carefully so that part of its water of crystallisation is removed, giving CaSO₄·½H₂O. Therefore option A is correct. Option B is gypsum, the starting material; option C is washing soda; and option D is baking soda. The half-water notation represents the average water content per calcium sulphate unit.
Frequently asked questions
What is the correct answer to this question?
CaSO₄·½H₂O
Why is this the correct answer?
Plaster of Paris is calcium sulphate hemihydrate. During its preparation, gypsum, CaSO₄·2H₂O, is heated carefully so that part of its water of crystallisation is removed, giving CaSO₄·½H₂O. Therefore option A is correct. Option B is gypsum, the starting material; option C is washing soda; and option D is baking soda. The half-water notation represents the average water content per calcium sulphate unit.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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