Which one of the following statements is incorrect regarding an electrochemical cell? — Electrochemistry Chemistry Question

💡 Solution & Explanation

Step 1 - Define the Fundamentals of an Electrochemical Cell An electrochemical cell (specifically a galvanic or voltaic cell) is a device that converts chemical energy from spontaneous redox reactions into electrical energy. The system is divided into two half-cells: * **Anode (Oxidation half-cell):** Where oxidation (loss of electrons) occurs. * **Cathode (Reduction half-cell):** Where reduction (gain of electrons) occurs. Step 2 - Analyze Statement (A): "The electrode on which oxidation takes place is called anode." In electrochemistry, the anode is universally defined as the electrode where oxidation takes place, regardless of whether the cell is galvanic (electrochemical) or electrolytic. The general oxidation reaction is represented as: $$\ce{M(s) -> M^{n+}(aq) + n e^-}$$ Thus, this statement is **correct**. Step 3 - Analyze Statement (B): "Anode is the negative pole." In a spontaneous electrochemical cell, the oxidation reaction at the anode releases electrons, which accumulate on the electrode surface before flowing through the external circuit. Because the anode is the source of electrons, it is designated as the negative terminal (negative pole) of the cell. Thus, this statement is **correct**. Step 4 - Analyze Statement (C): "The direction of the current is same as that of the direction of flow of electrons." By physical convention, the direction of conventional electric current is defined as the direction of flow of a positive charge, which is opposite to the direction of flow of negatively charged electrons: * **Electron flow direction:** From the negative electrode (anode) to the positive electrode (cathode) through the external metallic wire. * **Conventional current direction:** From the positive electrode (cathode) to the negative electrode (anode) through the external circuit. Since the direction of the conventional current is opposite to the direction of the electron flow, this statement is **incorrect**. Step 5 - Analyze Statement (D): "The flow of current is partly due to flow of electrons and partly due to flow of ions." A complete, functional electrical circuit in an electrochemical cell consists of two main parts: 1. **External Circuit (Metallic Conduction):** Electric current is carried by the flow of free electrons through the copper wires and external devices connecting the two electrodes. 2. **Internal Circuit (Ionic Conduction):** Electric current is carried by the migration of mobile anions and cations through the electrolyte solutions and the salt bridge. Therefore, the total current flow in the complete cell loop is indeed due partly to the movement of electrons and partly due to the movement of ions. Thus, this statement is **correct**. Step 6 - Conclusion Since statement (C) is the only incorrect statement regarding an electrochemical cell, it is the correct choice for this question. $$\text{Correct Option: } \boxed{\text{C}}$$