Chemical reactions are represented by chemical equations, shown either as part of the main body of the text (for short equations) or set separately from the text. If set separately, equations can be numbered, in the same way as mathematical equations (see Displaying equations in text):
NaOH + HCl → NaCl + H2O (1)
A number of conventions are used for arrows within chemical equations. For example, a single arrow (→) is used to indicate a reaction that is proceeding in one direction, whereas 2 arrows in opposite directions (⇄) show a reaction that is proceeding in both directions:
Two half arrows in opposite directions indicate a reaction at equilibrium:
