Calcium Sulphate Hemihydrate 96% Letterbox Friendly Pouch


Calcium sulphate (or calcium sulfate) is a common laboratory and industrial chemical. In the form of gamma-anhydrite (the nearly anhydrous form), it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulphate is a translucent, crystalline white rock. When sold as a colour-indicating variant under the name Drierite, it appears blue or pink due to impregnation with Cobalt(II) chloride, which functions as a moisture indicator. The hemihydrate (CaSO4.~0.5H2O) is better known as plaster of Paris, while the dihydrate (CaSO4.2H2O) occurs naturally as gypsum. The anhydrous form occurs naturally as beta-anhydrite. Depending on the method of calcination of calcium sulphate dihydrate, specific hemihydrates are sometimes distinguished: alpha-hemihydrate and beta-hemihydrate. They appear to differ only in crystal shape. Alpha-hemihydrate crystals are more prismatic than beta-hemihydrate crystals and, when mixed with water, form a much stronger and harder superstructure.

  • Used as a common component of fouling deposits in industrial heat exchanges

Minimum Assay: <96%
Molecular Formula: CaO4S
Molecular Weight: 136.14
Solubility in water: 0.24g in 100g water
Melting Point:  1450°C
Density (g/cm3): 2.96
Loss on ignition: <2.85%

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 7778-18-9
Einecs No: 231-900-3

HS CODE: 2520100000


Following the UK’s departure from the EU on 1 January 2021, all European shipments are sent on a DAP Basis (Delivered at Place).

This means that the buyer will be liable for import VAT at their prevailing national rate and for orders over 150€ (including carriage) import duties will become chargeable at your prevailing national rate.

The Duty is ascertained by your national customs authority based on the HS Code of each product. The HS Code is shown in the “European Shipment” section of each product page.


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