Citric acid is an important organic acid, also known as citric acid, colorless crystal, often containing one molecule of water of crystallization, odorless, strong acidity, and soluble in water. Its calcium salt is easily dissolved in cold water than hot water, and this property is commonly used to identify and separate citric acid. Anhydrous citric acid can be obtained by controlling a suitable temperature during crystallization. It has many uses in industry, food industry, and cosmetics industry.
1. Physical properties at room temperature, citric acid as colorless crystals or white translucent particles or white crystalline powder, odorless, very sour taste, astringency, weakly corrosive, strongly deliquescent, water of crystallization accompanied The compound is formed and is slightly deliquescent in moist air. It may exist in the form of an anhydrate or a monohydrate: when citric acid is crystallized from hot water, an anhydrate is formed; when crystallized in cold water, a monohydrate is formed. Upon heating to 78 ° C, the monohydrate will decompose to give an anhydrate. At 15 degrees Celsius, citric acid can also be dissolved in absolute ethanol. The crystal form of citric acid varies depending on the crystallization conditions. There are anhydrous citric acid C6H8O7 and citric acid 2C6H8O7.H2O, C6H8O7.H2O or C6H8O7.2H2O containing crystal water.
2. Structurally citric acid is a tricarboxylic acid compound and thus has similar physical and chemical properties to other carboxylic acids. When heated to 175 °C it will decompose to produce carbon dioxide and water, leaving some white crystals. Citric acid is a strong organic acid. There are 3 H+s that can be ionized. Heating can be decomposed into various products and react with acids, bases and glycerol.
|
