1. Ammonia is a colorless and toxic gas with a special odor at normal temperature and pressure, which is lighter than air. Ammonia is stable at room temperature, but can be decomposed into hydrogen and nitrogen at high temperatures. Generally, it decomposes at 450-500℃ under one atmospheric pressure. If there are catalysts such as iron and nickel, it can decompose at 300℃. 2NH3---------3H2+N2.

2. The molecular weight of ammonia is 17.031, the boiling point in the standard state is -33.35°C, the critical temperature is 132.4°C, the critical pressure is 1127Kpa, the critical specific volume is 4.130L/kg, and the solidification temperature in the standard state is -77.7°C.

3. Ammonia is combustible in the air, but it is generally difficult to catch fire. If it is continuously exposed to the fire source, it will burn, and sometimes it can cause an explosion. If there is grease or other combustible substances, it is more likely to catch fire. When burned in oxygen, it emits a yellow flame and produces nitrogen and water. 4NH3+3O2----------2N2+6H2O.

4. Ammonia can also explode in nitrous oxide, and the explosive concentration limit is 2.2%-72%.

5. Ammonia is slightly soluble in methanol, ethanol, dichloromethane and ether.

6. The latent heat of vaporization of liquid ammonia is second only to that of water, and it is 301.8Cal/g at 0°C. So it has water-like properties and can dissolve many substances. The solution also shows many properties similar to the aqueous solution. Liquid ammonia can dissolve ammonium salts, and various metals can sell hydrochloric acid, iodides, phenols and amines.

7. Ammonia is toxic. The maximum allowable concentration is 25ppm (18mg/m³). Ammonia is mainly inhaled through the respiratory tract and can also be absorbed through the skin. Ammonia is dangerous when mixed with certain substances.