Calcium Hydroxide

Calcium Hydroxide BP British Pharmacopoeia

Ca(OH)2 -- 74.1

Preparation
Calcium Hydroxide SolutionDEFINITION
Content
95.0 per cent to 100.5 per cent.

CHARACTERS
Appearance
White or almost white, fine powder.
Solubility
Practically insoluble in water.

IDENTIFICATION
A. To 0.80 g in a mortar, add 10 ml of water R and 0.5 ml of phenolphthalein solution and mix. The suspension turns red. On addition of 17.5 ml of 1 M hydrochloric acid , the suspension becomes colourless without effervescing. The red colour occurs again when the mixture is triturated for 1 min. On addition of a further 6 ml of 1 M hydrochloric acid and triturating, the solution becomes colourless.
B. Dissolve about 0.1 g in dilute hydrochloric acid and dilute to 10 ml with water . 5 ml of the solution give reaction of calcium.

TESTS
Matter insoluble in hydrochloric acid
Maximum 0.5 per cent.
Dissolve 2.0 g in 30 ml of hydrochloric acid. Boil the solution and filter. Wash the residue with hot water. The residue weighs a maximum of 10 mg.
Carbonates
Maximum 5.0 per cent of CaCO3.
Chlorides
Maximum 330 ppm.
Sulphates
Maximum 0.4 per cent.
Arsenic
Maximum 4 ppm.
Magnesium and alkali metals
Maximum 4.0 per cent calculated as sulphates.
Heavy metals
Maximum 20 ppm.

ASSAY
To 1.500 g in a mortar, add 20-30 ml of water R and 0.5 ml of phenolphthalein solution. Titrate with 1 M hydrochloric acid by triturating the substance until the red colour disappears. The final solution is used in the tests for carbonates.
1 ml of 1 M hydrochloric acid is equivalent to 37.05 mg of Ca(OH)2.


Calcium Hydroxide USP Ca(OH)2

Calcium Hydroxide; Lime
Ca(OH)2 -- 74.09
Calcium hydroxide [1305-62-0].
Calcium Hydroxide contains not less than 95.0 percent and not more than 100.5 percent of Ca(OH)2.