What is calcium sulphate commonly called?

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water.

The main use of calcium sulfate is to produce plaster of Paris and stucco. These applications exploit the fact that calcium sulfate which has been powdered and calcined forms a moldable paste upon hydration and hardens as crystalline calcium sulfate dihydrate. It is also convenient that calcium sulfate is poorly soluble in water and does not readily dissolve in contact with water after its solidification.

More Info: en.wikipedia.org

Test your knowledge

What are your thoughts on this subject?

38 Comments

Jim Hubbard

Good question! Chalk= calcium carbonate https://en.wikipedia.org/wiki/Chalk Milk of Magnesia= magnesium hydroxide https://en.wikipedia.org/wiki/Magnesium_hydroxide Slaked lime=calcium hydroxide https://en.wikipedia.org/wiki/Calcium_hydroxide

Mark Snyder

I knew the answer wasn't edible.

Marianne Hays

Good question even though I missed it. Thank you.

robert karel

Brendan Grainger, are you sure you can remember that far back?

robert karel

Naadia Marshall, Me too!

gatorguerry

Anhydrite = anhydrous calcium sulfate Hemihydrate = calcium sulfate with one molecule of water of hydration Dihydrate or gypsum = calcium sulfate with 2 moles pf water of hydration. Plaster of Paris results from mixing the hemihydrate with water to form gypsum upon drying.

Andrew Allan

Strictly speaking Plaster of Paris is HYDRATED calcium carbonate

Irene Townsend

Very good question and explanation

Lynne Zeman

Absolutely no clue.

Helen Keen

I would have enjoyed taking chemistry from you! Bruce Cassamajor,

Brendan Grainger

The 'chalk' used for the blackboards I was led to believe by my chemistry teacher was Calcium Sulphate.

Ruth Cost

Curious why only once in awhile there's a place for comments on questions? Would like to see it for every question. Often have either questions or would like to debate the answer, lol

segarolow

Good one....

Vic Afalla

= Plaster of Paris...

Bruce Cassamajor

Less 20 % of the participants have a basic knowledge chemistry. Winners are 20 % only, not all from knowledge of chemistry. What does that tell? Either 80% have never had a class of chemistry, or their chemistry class was only repeating Calcium Sulphate, but never told them what is its practical application. That is the main component of our sheetrock- our building material, very common. It is either mined or prepared with calcium carbonate (the chalk material) and sulphate, the by-product of petroleum mining (fossil fuel). Calcium Sulphate is also called gypsum. In my chemistry lessons, I bring to class every thing I can touch or think of to show the students what we are talking about. I bring piece of sheetrock, chalk, garden lime, and all other material containing calcium or calcium sulphate, including casting plaster or a picture of casting. Like wise when I teach carbon, I bring charcoal, asphalt, black carbon, water filter, carbon paper, etc. It is time for the students, who have a class of chemistry, to know what are the compounds of each element, they repeat, in their class, are used for.