Quick Lime, when freshly ignited to constant weight, contains not less than 95.0 percent of CaO, Calcium Oxide.
Identification—
A: Moisten it with water: heat is generated, and a white powder is obtained (calcium hydroxide or slaked lime). Mix the powder with 3 or 4 times its weight of water: a
smooth magma of lime forms that is alkaline to litmus.
B: Slake 1 g of Lime or Calcium Oxide with 20 mL of water, and add 6 N acetic acid until the lime is dissolved: the resulting solution responds to the test for Calcium.
Loss on ignition— Ignite a portion of Quick Lime or Calcium Oxide to constant weight in a tarred platinum crucible at 1100 ± 50 C it loses not more than 10.0%
of its weight.
Insoluble substances— Slake 5.0 g of Quick Lime or Calcium Oxide, then mix with 100 mL of water, followed by hydrochloric acid, drop wise, with agitation, until
solution takes place: the resulting solution after boiling and cooling is acid, and when filtered through a tarred crucible, washed with water until free of chlorides,
and dried at 105 for 1 hour yields not more than 50 mg of insoluble substances (1.0%).
Carbonate— Slake 1 g, mix with 50 mL of water, and decant the greater portion of the milky liquid: the addition of an excess of 3 N hydrochloric acid to the
residue does not cause more than a slight effervescence.
Magnesium and alkali salts— Dissolve 500 mg in 30 mL of water and 15 mL of 3 N hydrochloric acid. Neutralize the solution with 6 N ammonium hydroxide, heat to
boiling, and add ammonium oxalate TS to precipitate the calcium completely. Heat the mixture on a steam bath for 1 hour, cool, dilute with water to 100 mL, mix, and
filter. To 50 mL of the filtrate add 0.5 mL of sulfuric acid, evaporate to dryness, and ignite in a tarred platinum crucible to constant weight. The weight of the
residue does not exceed 9 mg.
Assay— Ignite about 1 g of Lime in a muffle furnace to constant weight, cool, weigh accurately, and dissolve in 20 mL of 3 N hydrochloric acid. Cool the solution,
transfer to a 500-mL volumetric flask with the aid of water, dilute with water to volume, and mix. Transfer 50.0 mL to a suitable container, add 100 mL of water, 15 mL
of 1 N sodium hydroxide, and 300 mg of hydroxy naphthol blue, and titrate with 0.05 M edta disodium VS until the solution is deep blue in color. Each mL of 0.05 M
edta disodium is equivalent to 2.804 mg of CaO.
Lime or Quick Lime
CaO Formula wt 56.08
Calcium Oxide FCC Food Grade
INS: 529 CAS: [1305-78-8]
DESCRIPTION
Quick Lime or Calcium Oxide occurs as hard, white or gray-white masses or granules, or as a white to gray-white powder. One gram dissolves in about 840 mL of water
at 25° and in about 1740 mL of boiling water. It is soluble in glycerin but insoluble in alcohol.
Function: pH control agent; nutrient; dough conditioner; yeast food.
REQUIREMENTS
Identification: Slake Quick Lime or Calcium Oxide 1 g of sample with 20 mL of water, and add glacial acetic acid until the sample is dissolved. The resulting
solution gives positive tests for Calcium.
Assay: Not less than 95.0% and not more than 100.5% of CaO (Lime or Calcium Oxide ) after ignition.
Acid-Insoluble Substances: Not more than 1%.
Alkalies or Magnesium: Not more than 3.6%.
Arsenic: Not more than 3 mg/kg.
Fluoride: Not more than 0.015%.
Lead: Not more than 2 mg/kg.
Loss on Ignition: Not more than 10.0%.
