In analytical chemistry, sodium hydroxide and potassium hydroxide can often be used interchangeably with Du.
However, in some application fields, the two can not be replaced.
For example, hydrogen generating Dao generator is specified to use potassium hydroxide.
Sodium lime for medical use, sodium hydroxide as specified.
The hygroscopicity of sodium hydroxide is stronger than that of potassium hydroxide, so potassium hydroxide is commonly used in chemical analysis. Similarly, if it is used as a desiccant, sodium hydroxide should be used. For example, for medical sodium lime, sodium hydroxide is specified. But the price of two sodium hydroxide is cheaper, and sodium hydroxide is needed when it can be replaced.
Both of them have strong corrosivity, can't contact with metal container, and are easy to deliquescence. They should be sealed and stored.
There is no difference in the method of preservation and transportation.
The physical properties of sodium hydroxide are as follows
The purity is colorless and transparent crystal with relative density of 2.130. Melting point 318.4 ℃. Boiling point 1390 ℃. There are two kinds of caustic soda sold in the market: pure solid caustic soda is white, with block, flake, rod, granular and brittle; pure liquid caustic soda is colorless and transparent liquid. Solid caustic soda has strong hygroscopicity. It is soluble in water and exothermic when dissolved. The aqueous solution is alkaline and greasy; soluble in ethanol and glycerin; insoluble in acetone and ether. It has strong corrosivity and corrodes fibers, skin, glass, ceramics, etc. It reacts with aluminum and zinc, non-metallic boron and silicon to give out hydrogen, disproportionation with halogen such as chlorine, bromine and iodine, neutralizing with acids to form salt and water.
The physical properties of potassium hydroxide are as follows
White orthorhombic crystal, industrial products are white or light gray block or rod. The relative density was 2.044 (20 ℃). The melting point is 360.4 ℃. The boiling point is 1320 ～ 1324 ℃. It is easy to dissolve in water. When dissolved, it releases a large amount of heat of dissolution. It has strong water absorption. It can absorb water and dissolve in the air, and absorb carbon dioxide and gradually turn into potassium carbonate. Soluble in ethanol, slightly soluble in ether. It has strong alkalinity and corrosivity, and its properties are similar to that of caustic soda.