NOVELTY - Conducting equilibrium reaction and selectively separating reactive species of equilibrium reaction, comprises introducing a first composition comprising a metal halide into an apparatus, introducing a source of an elemental semiconductor, reacting the metal halide and elemental semiconductor in apparatus to produce a gaseous stream comprising a halide of the semiconductor, unreacted metal halide and elemental metal, condensing the unreacted metal halide and elemental metal with the halide of the semiconductor remaining in the gaseous stream, and isolating a portion of the gaseous stream.    USE - The method is useful for conducting an equilibrium reaction and selectively separating reactive species of the equilibrium reaction (claimed) for producing high purity semiconductors such as silicon and germanium in electronics applications including computer processors and solar energy applications such as solar cells.    ADVANTAGE - The method increases the yield and purity of the semiconductor.    DETAILED DESCRIPTION - Conducting an equilibrium reaction and selectively separating reactive species of the equilibrium reaction in an apparatus that is sealed from the ambient environment and that comprises a heating zone and an overhead temperature modulation zone in fluid communication with the heating zone, where the temperature of each zone is independently controlled, comprises: either introducing a first composition comprising a metal halide into an apparatus that is sealed from the ambient environment, introducing a source of an elemental semiconductor that is reactive with the metal halide into the apparatus, reacting the metal halide and the elemental semiconductor in the apparatus to produce a gaseous stream comprising a halide of the semiconductor, unreacted metal halide, and optionally elemental metal, where the reaction is an equilibrium reaction, condensing the unreacted metal halide and, when present, elemental metal from the gaseous stream with the halide of the semiconductor remaining in the gaseous stream, and isolating at least a portion of the gaseous stream including the halide of the semiconductor from the condensed metal halide and elemental metal after condensing the metal halide and, when present, elemental metal from the gaseous stream; or introducing a first composition comprising zinc chloride into the heating zone of the apparatus, introducing a source of an elemental silicon into the heating zone of the apparatus, reacting the zinc chloride in gaseous form and the elemental silicon in solid form to produce a gaseous stream comprising silicon tetrachloride, elemental zinc, and unreacted zinc chloride, feeding the gaseous stream comprising the silicon tetrachloride, elemental zinc and unreacted zinc chloride to the overhead temperature modulation zone of the apparatus, condensing the elemental zinc into solid or liquid form and the unreacted zinc chloride into liquid form from the gaseous stream in the overhead temperature modulation zone, with the silicon tetrachloride remaining in the gaseous stream, returning the condensed zinc chloride to the heating zone of the apparatus, isolating at least a portion of the gaseous stream including the silicon tetrachloride from the condensed zinc chloride and elemental zinc after condensing the zinc chloride and elemental zinc from the gaseous stream.