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For example, the end of a household battery marked with a "+" is the cathode (while discharging). In both a galvanic cell and an electrolytic cell, the anode is the electrode at which the oxidation reaction occurs. In a galvanic cell the anode is the wire or plate having excess negative charge as a result of the oxidation reaction.
For example, the electrolysis of brine produces hydrogen and chlorine gases which bubble from the electrolyte and are collected. The initial overall reaction is thus: [22] 2 NaCl + 2 H 2 O → 2 NaOH + H 2 + Cl 2. The reaction at the anode results in chlorine gas from chlorine ions: 2 Cl − → Cl 2 + 2 e −
An electrolytic cell is an electrochemical cell that utilizes an external source of electrical energy to force a chemical reaction that would otherwise not occur. [ 1 ] : 64, 89 [ 2 ] : GL7 The external energy source is a voltage applied between the cell's two electrodes ; an anode (positively charged electrode) and a cathode (negatively ...
Electrochemical cells that generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells. [2] Both galvanic and electrolytic cells can be thought of as having two half-cells: consisting of separate oxidation and reduction reactions.
The purpose of the divided cell is to permit the diffusion of ions while restricting the flow of the products and reactants. This separation simplifies workup. An example of a reaction requiring a divided cell is the reduction of nitrobenzene to phenylhydroxylamine, where the latter chemical is susceptible to oxidation at the anode.
The spontaneous redox reactions of a conventional battery produce electricity through the different reduction potentials of the cathode and anode in the electrolyte. However, electrolysis requires an external source of electrical energy to induce a chemical reaction, and this process takes place in a compartment called an electrolytic cell .
Without a membrane, the OH − ions produced at the cathode are free to diffuse throughout the electrolyte. As the electrolyte becomes more basic due to the production of OH −, less Cl 2 emerges from the solution as it begins to disproportionate to form chloride and hypochlorite ions at the anode: Cl 2 + 2 NaOH → NaCl + NaClO + H 2 O
Electrolyte can be fed on both anode and cathode side or anode side only. [10] In the zero-gap design of AWE, the electrodes are separated only by a diaphragm which separates the gases. The diaphragm only allows water and hydroxide ions to pass through, but does not completely eliminate gas cross-over.