Heating _______________ to 120°C yields plaster of Paris ?
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Answer: B. Gypsum
Explanation
Heating gypsum to approximately 120 degrees Celsius drives off part of its crystal water. This controlled dehydration converts calcium sulfate dihydrate into calcium sulfate hemihydrate. The resulting hemihydrate powder sets rapidly when mixed back with water to form molds. Gypsum is a naturally occurring mineral composed of calcium sulfate with bound water molecules. Plaster of Paris is the common name for the powdered hemihydrate product used in construction. Precise temperature regulation during calcination prevents formation of anhydrous dead burnt plaster.
Medical professionals use plaster of Paris casts to immobilize broken bones during healing. Sculptors and artisans rely on the material for making detailed decorative casts and molds. Building products manufacturing plants process millions of tons of gypsum into wallboard annually. Blue vitriol is copper sulfate pentahydrate which yields different thermal decomposition products. Calcium silicate is a high temperature refractory material rather than a plaster precursor. Calcium sulphate alone lacks the specific hydration state needed without referencing gypsum.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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