8.3 Homogeneous and heterogeneous catalysts

A catalyst increases reaction rate without being consumed overall. It provides an alternative pathway with lower activation energy.

A homogeneous catalyst is in the same phase as the reactants; a heterogeneous catalyst is in a different phase and often acts at a surface. Neither changes ΔH or the equilibrium constant.

An iron catalyst in the Haber process speeds both forward and reverse reactions so equilibrium is reached sooner, but the final ammonia composition is unchanged.

A catalyst does not increase the energy of particles or make an endothermic reaction exothermic. It changes the pathway, not the thermodynamic endpoints.