Ammonia

Ammonia is the neutral molecule NH3. When it accepts a proton it becomes the positively charged ammonium ion, NH4+. In water an equilibrium exists between NH3 and NH4+; because ammonium’s pKa is about 9.25, at physiological/neutral pH most nitrogen is present as NH4+, while at higher (basic) pH more exists as NH3.

Yes. Ammonia is a corrosive gas and aqueous solution that can harm humans. Low concentrations irritate eyes, nose, throat and skin; higher or prolonged exposures can cause chemical burns, severe respiratory injury (including pulmonary edema), and even death. Chronic exposure may trigger airway inflammation or asthma-like symptoms. For exposure, move to fresh air, flush affected skin/eyes with water, remove contaminated clothing, and seek medical attention for significant symptoms.

Ammonia is used primarily as a fertilizer feedstock (ammonium compounds), a refrigerant in industrial cooling systems, and a building block for chemicals, plastics, and explosives. It appears in household cleaners, water treatment and pH control, laboratory reagents, and smelling salts/medical stimulants. Industry also uses it for metal treatment and textile production. Its versatility requires careful handling due to toxicity and corrosiveness.

Ammonia is a nitrogen-containing waste produced when proteins and amino acids are broken down, and by gut bacteria. The liver converts ammonia into urea via the urea cycle for safe excretion by the kidneys. Excess ammonia is toxic to the brain and can cause confusion, lethargy, or coma, particularly in liver failure or metabolic disorders, so the body tightly regulates its levels.

Ammonia (NH3) is toxic because the un‑ionized form diffuses across fish gills, disrupting ionoregulation and acid–base balance, damaging gill tissue and impairing oxygen uptake. It interferes with cellular respiration and neural function, causing metabolic and neurological failure. Toxicity increases with higher pH and temperature, which raise the proportion of NH3 versus the less‑toxic NH4+, leading to rapid stress and mortality.

Ammonia is produced industrially by the Haber–Bosch process, combining nitrogen (N2) and hydrogen (H2) over an iron catalyst at ≈400–500°C and 150–300 atm to yield NH3; hydrogen commonly comes from steam‑reformed natural gas or electrolysis. Biologically, ammonia forms during protein and amino‑acid breakdown and via nitrogen‑fixing or decomposing microbes; animals convert excess ammonia to urea for excretion.