To find the chemical formula of sodium acetate trihydrate
. To know the chemical formula of sodium acetate trihydrate, when its constituent elements are known. Sodium acetate is composed of sodium ion ($Na ^ + $) and acetate ion ($CH_3COO ^ - $). And trihydrate means that each molecule of sodium acetate carries three parts of crystal water.

The chemical formula of water molecule is $H_2O $. In acetate ion, the number of atoms of carbon ($C $), hydrogen ($H $), and oxygen ($O $) is fixed. In acetate ion, carbon has two atoms, hydrogen has three atoms, and oxygen has two atoms.

Sodium ions and acetate ions combine in a ratio of 1 dollar: 1 $to form sodium acetate, and its anhydrous chemical formula is $CH_3COONa $.

Because it is a trihydrate, it is necessary to add three-dimensional crystal water after the chemical formula of sodium acetate. The chemical formula of sodium acetate trihydrate is $CH_3COONa\ cdot3H_2O $.