Langmuir Isotherm Calculator

The Langmuir model assumes monolayer adsorption onto a homogeneous surface with no interaction between adsorbed molecules. The core mathematical relationship is defined by the equation: surface_fraction = (eq_constant * partial_pressure) / (1 + (eq_constant * partial_pressure)). To express this value as a percentage, the surface fraction is multiplied by 100 to yield the surface percent.

Imagine you are studying the adsorption of carbon monoxide on a metal catalyst at a specific temperature. Let us assume your equilibrium adsorption constant (K) is 2.5 kPa^-1, and the gas partial pressure (P) is 0.4 kPa. First, multiply the constant by the pressure: 2.5 * 0.4 = 1.0. Next, add 1 to this product for the denominator: 1 + 1.0 = 2.0. Then, divide the numerator by the denominator: 1.0 / 2.0 = 0.5, giving a surface fraction of 0.5. Finally, multiply by 100 to find that 50% of the available surface is covered.

Ensure your units for the equilibrium constant and partial pressure are reciprocal to one another (e.g., if pressure is in kPa, the constant should be in kPa^-1). Remember that the Langmuir model strictly assumes monolayer coverage, meaning it may lose accuracy at extremely high pressures where multilayer condensation begins to occur.