Chemical equation

In chemistry, a chemical equation is a symbolic representation of a chemical reaction. For example, the combustion of methane in oxygen is

CH₄ + 2 O₂ → CO₂ + 2 H₂O,

and the reversible reaction[?] of the Haber process is

N_2(g) + 3H_2(g) <--> 2NH_3(g) + ΔH.