Calcium hydroxide
Description
A soft, white, alkaline powder. Calcium hydroxide, or slaked lime, is made by grinding quicklime (Calcium oxide) with water; this forms a fine-grain precipitate. Calcium hydroxide absorbs carbon dioxide from the air forming Calcium carbonate. It is used as a component in hydraulic cements because it will set underwater. Calcium hydroxide is also used to dehair hides, to kill insects, as a preservative in water paints and as a neutralizing agent in paper pulp solutions. A saturated solution of calcium hydroxide, called Limewater, has a pH of 12.4.
Synonyms and Related Terms
calcium dihydroxide; slaked lime; calcium hydrate; lime hydrate; caustic lime; limewater
Other Properties
Soluble in glycerin, acids. Slightly soluble in water. pH = 12.4 (saturated solution)Insoluble in alcohols.
| Composition | Ca(OH)2 |
|---|---|
| CAS | 1305-62-0 |
| Melting Point | 580 (dec) |
| Density | 2.08-2.34 |
| Molecular Weight | mol. wt. = 74.1 |
Hazards and Safety
Skin contact causes irritation.
International Chemical Safety Card
Additional Information
T.Schaeffer, V.Blythe-Hill, J.Druzik "Aqueous Light Bleaching of Paper: Comparison of Calcium Hydroxide and Magnesium Bicarbonate Bathing Solutions" JAIC, 35:219-238, 1996.
Sources Checked for Data in Record
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 505
- Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
- Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989