Theory of chemical equilibrium in a lattice

The chemical equilibrium is studied for the reaction A+B↔C, assuming that, initially, the particles B form a lattice and the particles A are statistically distributed on interstices. A mass action law is derived which defines the numbers nA, nB, nC of particles A, B, C in the chemical equilibrium assuming the initial distribution to be known. It predicts a considerably larger number nC of fused particles C compared to the mass action law for the gaseous phase. The result holds for an ordinary as well as for a nuclear lattice. Its possible relevance for the production of proton-rich isotopes in the universe is discussed. (orig.)