A concentration cell consists of two {{{\rm{Zn}}} \mathord{\left/ {\vphantom {{{\rm{Zn}}} {{\rm{Zn \right. \kern-\nulldelimiterspace} {{\rm{Zn^{2 + } half-cells. The concentration of Zn2+ in one of the half-cells is 2.0 M and the concentration in the other half-cell is 1.0×10−3M. Indicate the half-reaction occurring at each electrode.

Express your answers as chemical equations separated by a comma. Identify all of the phases in your answer.