Ammonium bicarbonate
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Ammonium Bicarbonate also called bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, or powdered baking ammonia is the bicarbonate salt of ammonia.
It is an irritant to the skin, eyes and respiratory system.
It was used in the food industry as a raising agent before the introduction of baking soda.
Ammonium bicarbonate, NH4HCO3, is formed as shown above and also by passing carbon dioxide through a solution of the normal compound, when it is deposited as a white powder, which has no smell and is only slightly soluble in water. The aqueous solution of this salt liberates carbon dioxide on exposure to air or on heating, and becomes alkaline in reaction. The aqueous solutions of all the carbonates when boiled undergo decomposition with liberation of ammonia and of carbon dioxide:
- NH4HCO3 → NH3 + H2O + CO2
- It is therefore occasionally used as baking powder, e.g. for gingerbread.
Physical properties
At room temperature it is a white powder. It dissolves in water to give a slightly alkaline solution. The process of dissolving is endothermic (as it is with many ammonium salts) and so causes a drop in the temperature of the water.
Chemical properties
- Reaction with acids gives carbon dioxide
- Reactions with alkalis gives ammonia
- It's chemical formula is NH4HCO3.
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