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CAS No.: | 1345-05-7 |
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Name: | Lithopone |
Molecular Structure: | |
Formula: | BaO5S2Zn2 |
Molecular Weight: | 412.23 |
Synonyms: | Pigment White 5;Barium zinc sulfate sulfide; |
EINECS: | 215-715-5 |
Density: | 4.136-4.39 g/cm3 |
Appearance: | White powder |
Hazard Symbols: | Xi,N |
Risk Codes: | R41; R43; R50/53; R36 |
PSA: | 137.80000 |
LogP: | 0.26720 |
Zinc and its compounds, as well as barium and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory.
Lithopone(CAS NO.1345-05-7) is a white pigment, a mixture of barium sulfate and zinc sulfide. It is also called C.I. 77115; Pigment White 5; Barium zinc sulfate sulfide and belongs to Product Categories of Inorganic & organic chemicals; uvcbs-inorganic. Lithopone is used in water-based paints because of its excellent alkali resistance. It is also used as a whitener and reinforcing agent for rubber and as a filler and whitener for paper. Poison because it can liberate hydrogen sulfide upon decomposition by heat, moisture, and acids. When heated to decomposition it emits highly toxic fumes of SOx, ZnO, and H2S. See also zinc, barium compounds (soluble), sulfides and hydrogen sulfide.
Preparation of Lithopone: Lithopone(CAS NO.1345-05-7) is manufactured by a process in which barium sulfide solution is prepared by reducing barite ore (BaSO4) with carbon and leaching the resulting mass.
BaSO4 + 4C → BaS + 4CO
Scrap zinc or concentrated zinc ores are dissolved in sulfuric acid, the solution is purified and the two solutions are reacted. A heavy mixed precipitate results that is 28 to 30% zinc sulfide and 72 to 70% barium sulfate.
ZnSO4 + BaS → ZnS + BaSO4
This precipitate is not suitable for a pigment until it is filtered, dried, crushed, heated to a high temperature and quenched in cold water. The second heating in a muffle furnace at 725 °C produces crystals of the right optical size.