The ion, NH4+, formed by combination of NH3 and H+ (the pKa value is 9.24); behaves as a univalent metal in forming a. compounds.
- a. chloride NH4Cl; a stimulant expectorant and cholagogue; used to relieve alkalosis and to promote lead excretion; a urinary acidifier. SYN: sal ammoniac.
- dibasic a. phosphate (NH4)2HPO4; used for fireproofing, in baking powder, and as an antirheumatic.
- a. ferric sulfate SYN: ferric a. sulfate.
- a. ichthosulfonate SYN: ichthammol.
- a. iodide NH4I; an expectorant.
- a. molybdate used in electron microscopy as a negative stain, and as a reagent for alkaloids and other substances.
- a. nitrate used in making nitrous oxide gas, in freezing mixtures, matches, and fertilizers; also used in veterinary medicine.
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am·mo·ni·um ə-'mō-nē-əm n an ion NH4+ derived from ammonia by combination with a hydrogen ion and known in organic compounds (as quaternary ammonium compounds) and in compounds (as salts) that resemble in properties the compounds of the alkali metals
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am·mo·ni·um (ə-moґne-əm) the hypothetical radical, NH4; it forms salts analogous to those of the alkaline metals.Medical dictionary. 2011.