TeXipedia

xrightleftharpoons

Represents a bidirectional chemical reaction or equilibrium with text above the arrows, commonly used in chemical equations.

Overview

Serves as an enhanced notation for chemical equilibrium reactions, allowing descriptive text to be placed above the double-headed harpoon arrows to indicate reaction conditions or other important information.

  • Essential in physical chemistry for showing reversible reactions with specific conditions
  • Frequently used when describing reaction mechanisms or kinetics
  • More detailed than simple double arrows, offering better clarity for complex chemical processes
  • Particularly valuable in academic papers and textbooks where reaction conditions need explicit notation

Examples

Reversible enzyme reaction with substrate and product.

E+S⇌koffkonESE + S \xrightleftharpoons[k_{off}]{k_{on}} ES 
E + S \xrightleftharpoons[k_{off}]{k_{on}} ES

Acid-base equilibrium with pH conditions.

H3O++OH−⇌basicacidic2H2O\text{H}_3\text{O}^+ + \text{OH}^- \xrightleftharpoons[\text{basic}]{\text{acidic}} 2\text{H}_2\text{O} 
\text{H}_3\text{O}^+ + \text{OH}^- \xrightleftharpoons[\text{basic}]{\text{acidic}} 2\text{H}_2\text{O}