Sodium acetate trihydrate is a hydrated, meaning water-containing, salt compound commonly used both industrially and in home chemical applications. The salt is derived from vinegar, and as such, has a vinegar-like taste and smell. It can be easily made at home by mixing vinegar with baking soda, and has distinct chemical properties.
Chemically, sodium acetate trihydrate is a white crystalline powder, notes the "CRC Handbook of Chemistry and Physics." While sodium acetate is a salt in its own right, the salt tends to combine with water from the air, leading to formation of the trihydrate, meaning each molecule of sodium acetate salt is combined with three molecules of water. The trihydrate salt has identical chemical properties to sodium acetate without water, but has different physical properties.
According to the "CRC Handbook of Chemistry and Physics," sodium acetate trihydrate is a solid at room temperature, with a melting point of 136 degrees Fahrenheit and a boiling point of 252 degrees Fahrenheit. The crystals dissolve easily in water, and when they do, the components of the salt--sodium, acetate and the water molecules--separate from one another through a process known as dissociation. This causes solutions of sodium acetate trihydrate to conduct electricity.
Sodium acetate trihydrate consists of three separate chemical components--sodium, acetate and water--only one of which is actually chemically reactive. Sodium and water don't engage in chemical reactions in which sodium acetate trihydrate participates, but the acetate portion of the molecule is a weak base, and can be used to make buffer solutions, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry." A buffer solution is one that resists changes in pH, or acidity.
Chemically, sodium acetate trihydrate is derived from vinegar, whose chemical name is acetic acid. When acetic acid reacts with a sodium-containing base, such as sodium bicarbonate, or baking soda, the products include sodium acetate salt. The acetate maintains many of the chemical properties of vinegar, including having a very similar taste, though vinegar is acidic while acetate is mildly basic, note Drs. Campbell and Farrell. Sodium acetate trihydrate is nontoxic and is sometimes used in vinegar-flavored foods.
Because sodium acetate trihydrate salt contains water, when the salt melts, it forms a solution of sodium acetate dissolved in water. Most salts, such as table salt--NaCl--melt at exceedingly high temperatures. This is because there is no water incorporated into the salt matrix, and melting the salt literally involves making molten salt, which requires high heat. Sodium acetate trihydrate contains the water necessary to dissolve the salt, such that melting occurs at much lower temperatures. In fact, "melting" sodium acetate trihydrate involves dissolving the salt in its own water more than true "melting."