Apatite treated with sulphuric acid gets converted to
mono calcium dihydrogen phosphate [Ca(H2PO4)2]
which is called superphosphate.
Calcium dihydrogen phosphate is more water-soluble
Monobasic calcium phosphate is primarily used in fertilizers. It also is used in baking powders; as a mineral supplement in food; as a buffer for pH control; and as a stabilizer for plastics.
calcium phosphate monobasic is an acidulant, leavening agent, and nutritional supplement that exists as white crystals or granular powder. It is sparingly soluble in water. It is used as an acidulant in breads and dry-mix beverages; as a source of calcium in fruit jellies, preserves, and cereals; and as a component of dough conditioners. It is also of restricted use as a chemical leavening agent because it releases about 67% of the carbon dioxide during the initial mixing and this is generally too rapid. It is also termed calcium acid phosphate, monocalcium phosphate, calcium biphosphate, and acid calcium phosphate.
Monobasic calcium phosphate may be prepared in the laboratory by the reaction of calcium carbonate with phosphoric acid:
CaCO3 + 2H3PO4 → Ca(H2PO4)2 + CO2 + H2O
Fertilizer grade product is obtained by pulverized phosphate rock (tricalcium phosphate) in phosphoric or sulfuric acid and evaporating the solution.
white, large, shining, tricl plates, crystal(s) powder(s) or granules; not hygroscopic [MER06] [STR93]
Monocalcium phosphate monohydrate was the first acidic phosphate used as a leavening acid. A patent for its use in baking powders was issued in 1956. The early MCP· H2 0 was prepared by ashing bones to form a crude product. This phosphate is classed as a fast-acting leavening acid; approximately 60% of the theoretical C02 is released by reaction of the MCP· H2 0 with soda during the mixing stage of batter or dough preparation. No further gas is then released until the product is placed in the oven and the temperature has reached approximately l40°F. The reason for this is that MCP· H2 0 disproportionates upon contact with water to form some dicalcium phosphate according to the following equation: Ca(H2PO4)2.H2O+H2O=CaHPO4.2H2O+H3PO4.Because of the speed of its reaction, MCP· H20 has limited applications by itself. Although it is commonly used in the preparation of phosphated flour at levels of 0.25 to 0.75% of the weight of the finished product and in the preparation of cookies, most of its applications are in combination with other slower-acting phosphate leavening acids. It is expected to release gas during the mixing stages to assist in forming bubble nucleii, while the other slower-acting acids release gas during bench action or baking.
Soil is made of particles of various sizes. Silt, a
constituent of soil, comprises particles of sizes between
those of clay and sand. According to the international
particle-size system, a silt particle size is about 2 to 50μm
in diameter. It is further divided into fine silt (2 to 20μm)
and coarse silt (20 to 50μm). The percentage of silt
particles in a particular soil is taken into consideration
while defining soil texture.
Silt is often carried as suspended particles in running
water and deposited on riverbeds, riverbanks or in lakes
as alluvial sediments.
A soil that contains 40% or more of clay and 40% or
more of silt is called silt clay. A soil with 27 to 40% clay
and less than 20% sand is known as silt-clay loam. Silt
loam has 30% or more silt and 12 to 27% clay. Similarly,
silt loam soil consists of 50 to 80% silt, less than 12%
clay and the rest sand.