Electrochemical Cells and Reversibility

An electrochemical cell is said to be reversible if the direction of the reaction cell is inverted when the electron flow is inverted. The cell is called irreversible if a new reaction cell appears when the electron flow is inverted. 

According to this definition, Daniell s galvanic cell and the corresponding electrolytic cell constitute a reversible cell. An example of an irreversible cell is provided 

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