According to the number of hydroxyl ions ionized by an alkali molecule, it can be divided into monobasic binary basic polybasic bases.

According to solubility: soluble alkali, slightly soluble alkali and insoluble alkali.

According to ionization ability: strong base and weak base.

According to use: industrial alkali and edible alkali.

Industrial alkali: it is a common name in the industry, with general meaning. It can be a variety of products, but generally refers to three kinds of alkali: industrial soda ash (sodium carbonate Na2CO3), industrial caustic soda (sodium hydroxide NaOH) and industrial heavy alkali (NaHCO3). Regardless of the above products, industrial alkali is an alkali with purity and impurity content (which may contain heavy metals, etc.). ) meet general industrial purposes. The process is relatively simple, and it can be produced on a large scale, which is harmful to human body.

Edible alkali: edible soda ash (sodium carbonate Na2CO3, with the same molecular formula, but without industrial soda ash impurities) and edible baking soda (sodium bicarbonate NaHCO3).