Ammonium Hydroxide Facts

What Ammonium Hydroxide Is and How It's Used

Girl preparing to spring clean
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Ammonium hydroxide is the name given to any aqueous (water-based) solution of ammonia. In pure form, it is a clear liquid that smells strongly of ammonia. Household ammonia usually is 5-10% ammonium hydroxide solution. Other names for ammonium hydroxide are:

  • Ammonia (e.g., household ammonia) [versus anhydrous ammonia]
  • Aqueous ammonia
  • Ammonia solution
  • Ammonia water
  • Ammonia liquor
  • Ammonical liquor
  • Spirit of Hartshorn

    Chemical Formula of Ammonium Hydroxide

    The chemical formula of ammonium hydroxide is NH4OH, but in practice, ammonia deprotonates some of the water, so the species found in solution are a combination of NH3, NH4+,, and OH in water.

    Ammonium Hydroxide Uses

    Household ammonia, which is ammonium hydroxide, is a common cleaner. It's also used as a disinfectant, food leavening agent, to treat straw for cattle feed, to enhance tobacco flavor, to cycle an aquarium without fish, and as a chemical precursor for hexamethylenetetramine and ethylenediamine. In the chemistry lab, it is used for qualitative inorganic analysis and to dissolve silver oxide.

    Concentration of Saturated Solution

    It's important for chemists to realize the concentration of a saturated ammonium hydroxide solution decreases as temperature increases. If a saturated solution of ammonium hydroxide is prepared at a cool temperature and the sealed container is heated, the concentration of the solution decreases and ammonia gas can build up in the container, potentially leading it to rupture.

    At a minimum, unsealing the warm container releases toxic ammonia vapors.

    Safety

    Ammonia in any form is toxic, whether it is inhaled, absorbed through the skin, or ingested. Like most other bases, it's also corrosive, which means it can burn skin or damage mucous membranes, such as eyes and the nasal cavity.

    It's also important to refrain from mixing ammonia with other household chemicals because they may react to release additional toxic fumes.