<P> A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left - hand side and the product entities on the right - hand side . The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers . The first chemical equation was diagrammed by Jean Beguin in 1615 . </P> <P> A chemical equation consists of the chemical formulas of the reactants (the starting substances) and the chemical formula of the products (substances formed in the chemical reaction). The two are separated by an arrow symbol (→ (\ displaystyle \ rightarrow), usually read as "yields") and each individual substance's chemical formula is separated from others by a plus sign . </P> <P> As an example, the equation for the reaction of hydrochloric acid with sodium can be denoted: </P> <Dl> <Dd> 2 HCl + 2 Na → 2 NaCl + H </Dd> </Dl>

What do double arrows in a chemical equation mean