Inorganic Chemicals

Formula: (NH4)2CO3•H2O; MW 114.10; not available in pure form; crystalline products consist of double salts of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate.

Synonyms: salt of hartshorn; sal volatile

Uses

Applications of ammonium carbonate are similar to those of ammonium bicarbonate. It is used in baking powder; in fire extinguishers; as mordant in dyeing; for washing and defatting wools; in tanning; in manufacture of rubber products; as a “smelling salt”; as a source of ammonia, and as an expectorant.

Physical Properties

Colorless or translucent hard crystalline mass or white cubic crystals or powder; sharp taste; odor of ammonia; decomposes at 58°C; slow decomposition at ambient temperatures; readily dissolves in cold water; decomposes in hot water; insoluble in liquid ammonia, alcohol and carbon disulfide.

Preparation

Ammonium carbonate is obtained by passing carbon dioxide into aqueous ammonia solution in a column or tower. Ammonia, carbon dioxide and water vapor are distilled and the vapors condensed into a solid crystalline mass. It also may be prepared by subliming a mixture of ammonium sulfate and calcium
carbonate.

Reactions

Ammonium carbonate slowly decomposes on exposure to air, or rapidly breaks down on heating to ammonia, CO2, and water; liberates CO2 on treatment with dilute mineral acids. It reacts with metals forming their carbonates. Reaction with hydriodic acid produces ammonium iodide; and forms ammonium oxalate with oxalic acid.