{"id":4094,"date":"2025-09-26T08:39:57","date_gmt":"2025-09-26T01:39:57","guid":{"rendered":"https:\/\/nhathuocngocanh.com\/bp\/?p=4094"},"modified":"2025-09-29T14:48:22","modified_gmt":"2025-09-29T07:48:22","slug":"calcium-hydroxide","status":"publish","type":"post","link":"https:\/\/nhathuocngocanh.com\/bp\/calcium-hydroxide\/","title":{"rendered":"Calcium Hydroxide"},"content":{"rendered":"

(Ph. Eur. monograph 1078)<\/p>\n

Ca(OH)2<\/sub>\u00a0 \u00a0 74.1\u00a0 \u00a0 1305-62-0<\/p>\n

Preparation<\/strong><\/p>\n

Calcium Hydroxide Solution<\/p>\n

DEFINITION<\/h2>\n

Content<\/h3>\n

95.0 per cent to 100.5 per cent.<\/p>\n

CHARACTERS<\/h2>\n

Appearance<\/h3>\n

White or almost white, fine powder.<\/p>\n

Solubility<\/h3>\n

Practically insoluble in water.<\/p>\n

IDENTIFICATION<\/h2>\n

A. To 0.80 g in a mortar, add 10 mL of water R and 0.5 mL of phenolphthalein solution R and mix. The suspension turns red. On addition of 17.5 mL of a 103 g\/L solution of hydrochloric acid R, 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 a 103 g\/L solution of hydrochloric acid R and triturating, the solution becomes colourless.<\/p>\n

B. Dissolve about 0.1 g in dilute hydrochloric acid R and dilute to 10 mL with water R. 5 mL of the solution give
\nreaction (b) of calcium (2.3.1).<\/p>\n

TESTS<\/h3>\n

Matter insoluble in hydrochloric acid<\/h3>\n

Maximum 0.5 per cent.<\/p>\n

Dissolve 2.0 g in 30 mL of hydrochloric acid R. Boil the solution and filter. Wash the residue with hot water R.<\/p>\n

The residue weighs a maximum of 10 mg.<\/p>\n

Carbonates<\/h3>\n

Maximum 5.0 per cent of CaCO3<\/sub>.<\/p>\n

Add 5.0 mL of 1 M hydrochloric acid to the titrated solution obtained under Assay and titrate with 1 M sodium hydroxide using 0.5 mL of methyl orange solution R as indicator.<\/p>\n

1 mL of 1 M hydrochloric acid is equivalent to 50.05 mg of CaCO3<\/sub>.<\/p>\n

Chlorides (2.4.4)<\/sub><\/h3>\n

Maximum 330 ppm.<\/p>\n

Dissolve 0.30 g in a mixture of 2 mL of nitric acid R and 10 mL of water R and dilute to 30 mL with water R.<\/p>\n

Sulfates (2.4.13)<\/h3>\n

Maximum 0.4 per cent.<\/p>\n

Dissolve 0.15 g in a mixture of 5 mL of dilute hydrochloric acid R and 10 mL of distilled water R and dilute to 60 mL with distilled water R.<\/p>\n

Elemental impurities<\/h3>\n

Any method that fulfils the requirements of general chapter 2.4.20. Determination of elemental impurities may be used.<\/p>\n\n\n\n\n\n
Element<\/td>\nMaximum content (ppm)<\/td>\n<\/tr>\n
Cadmium<\/td>\n1<\/td>\n<\/tr>\n
Lead<\/td>\n1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Magnesium and alkali metals<\/h3>\n

Maximum 4.0 per cent, calculated as sulfates.<\/p>\n

Dissolve 1.0 g in a mixture of 10 mL of hydrochloric acid R and 40 mL of water R. Boil and add 50 mL of a 63 g\/L solution of oxalic acid R. Neutralise with ammonia R and dilute to 200 mL with water R. Allow to stand for 1 h and filter through a suitable filter. To 100 mL of the filtrate, add 0.5 mL of sulfuric acid R. Cautiously evaporate to dryness and ignite. The residue weighs a maximum of 20 mg.<\/p>\n

ASSAY<\/p>\n

To 1.500 g in a mortar, add 20-30 mL of water R and 0.5 mL of phenolphthalein solution R. 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.<\/p>\n

1 mL of 1 M hydrochloric acid is equivalent to 37.05 mg of Ca(OH)2<\/sub>.<\/p>\n","protected":false},"excerpt":{"rendered":"

(Ph. Eur. monograph 1078) Ca(OH)2\u00a0 \u00a0 74.1\u00a0 \u00a0 1305-62-0 Preparation Calcium Hydroxide Solution DEFINITION 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…<\/p>\n","protected":false},"author":3,"featured_media":4108,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[174],"tags":[],"class_list":["post-4094","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicinal-substances"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/4094","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=4094"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/4094\/revisions"}],"predecessor-version":[{"id":5604,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/4094\/revisions\/5604"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/4108"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=4094"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=4094"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=4094"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}