Comparison of sodium acetate trihydrate and anhydrous sodium acetate
Sodium acetate, in the field of chemistry, two forms of sodium acetate trihydrate and anhydrous sodium acetate are common. The two have their own characteristics in many aspects.

1. Physical and chemical properties
1. ** Sodium acetate trihydrate **
Sodium acetate trihydrate, its chemical formula is $CH_3COONa · 3H_2O $. The appearance is often colorless and transparent or white granular crystalline, with a relative density of 1.45 and a melting point of about 58 ° C. It can be weathered in air, easily soluble in water, and its aqueous solution is alkaline. Because it contains crystal water, it shows a certain degree of deliquescence.
2. ** Anhydrous sodium acetate **
The chemical formula of anhydrous sodium acetate is $CH_3COONa $, the appearance is white powder, odorless, the relative density is 1.528, and the melting point is 324 ° C. Compared with sodium acetate trihydrate, anhydrous sodium acetate is drier and has relatively weak hygroscopicity, but its solubility in water is also considerable, and it also makes the aqueous solution alkaline.

Second, preparation method
1. ** Preparation of sodium acetate trihydrate **
is often prepared by reacting acetic acid with sodium hydroxide or sodium carbonate. For example, the reaction between acetic acid and sodium hydroxide is as follows: $CH_3COOH + NaOH → CH_3COONa + H_2O $. After the reaction, the crystal of sodium acetate trihydrate can be obtained through concentration, crystallization and other processes. This process is relatively simple to operate and the conditions are mild.
2. ** Preparation of anhydrous sodium acetate **
is usually obtained by heating and dehydration of sodium acetate trihydrate. During the heating process, the temperature and time need to be strictly controlled to ensure that the crystal water is completely removed to obtain anhydrous sodium acetate. If the temperature is not properly controlled, it is easy to cause the product to decompose or poor quality. For example, too high temperature may cause sodium acetate to decompose into products such as sodium carbonate and acetone.

III. Application field
1. ** Application of sodium acetate trihydrate **
Because it contains crystal water, it has unique advantages in some application scenarios that require high humidity. In the printing and dyeing industry, it can be used as a buffer to adjust the pH value of the dye solution and ensure uniform dyeing; in the food industry, it can be used as a preservative because its aqueous solution is alkaline and can inhibit the growth of microorganisms; in the field of wastewater treatment, it can be used as a carbon source for denitrifying bacteria to provide energy and promote the reduction of nitrates.
2. ** Application of anhydrous sodium acetate **
Anhydrous sodium acetate because it does not contain crystal water and has high purity. It is often used in laboratory chemical analysis and used as a standard reagent to calibrate acid solutions. In the field of organic synthesis, it is an important acetylation reagent. It participates in the synthesis reaction of many organic compounds, such as the reaction with halogenated hydrocarbons to prepare ester compounds.

Fourth, storage requirements
1. ** Sodium acetate trihydrate storage **
Because of its deliquescence, it needs to be stored in a dry and well-ventilated place to avoid contact with humid air. The humidity of the storage environment should be controlled within a certain range to prevent it from absorbing water and deliquescence, which affects the quality.
2. ** Anhydrous sodium acetate storage **
Although the hygroscopicity is relatively weak, it should still be stored in a dry environment to prevent moisture. At the same time, avoid mixing with acidic substances to prevent chemical reactions.

Sodium acetate trihydrate and anhydrous sodium acetate are both common forms of sodium acetate, but their physical and chemical properties, preparation methods, application fields and storage requirements are different. In practical applications, it is necessary to carefully select the appropriate form of sodium acetate according to specific needs.