Chemistry · Redox Equilibrium · NEET
| Reaction type | Spontaneous (EMF positive, Gibbs energy negative) | Non-spontaneous (needs external push) |
| Energy change | Chemical energy to electrical energy | Electrical energy to chemical energy |
| External battery | Not needed; it is the source | Required to drive the reaction |
| Anode sign | Negative | Positive |
| Cathode sign | Positive | Negative |
| Common example | Daniell cell, dry cell, discharging battery | Electrolysis of water, electroplating, charging a battery |
The galvanic cell runs on a spontaneous reaction (Gibbs energy change is negative, cell EMF is positive), so it produces current on its own. The electrolytic cell runs a non-spontaneous reaction (positive Gibbs energy), so it will not move until you push electrons in with an external battery. This is the single most tested difference in NEET, so lock it first.
Oxidation always happens at the anode and reduction always at the cathode in BOTH cells. The confusion is only about sign. In a galvanic cell the anode is negative and cathode is positive (the cell itself pushes electrons out from the anode). In an electrolytic cell the external battery decides the sign, so the anode is positive and cathode is negative. Rule to remember: the definition of anode = oxidation never changes; only the + / - label flips.
The Daniell cell (Zn in ZnSO4, Cu in CuSO4, joined by a salt bridge and a wire) is a galvanic cell. Zn is more reactive, so it spontaneously gives electrons to Cu2+, producing about 1.1 V without any external supply. NCERT introduces it as the model galvanic cell, so remember it as galvanic, not electrolytic.
A galvanic cell with two separate solutions needs a salt bridge (or porous barrier) to keep the solutions neutral and complete the circuit. A typical electrolytic cell has one electrolyte in one container with both electrodes dipped in it, so it usually does not need a salt bridge. This is a quick way to tell them apart in a diagram.
Galvanic cell: chemical energy converts to electrical energy (it makes current). Electrolytic cell: electrical energy converts to chemical energy (it drives a reaction, like electroplating or electrolysis of water). NEET loves to reverse this line, so read the direction of energy carefully.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A galvanic cell produces electricity from a spontaneous redox reaction, while an electrolytic cell uses electricity from an external source to drive a non-spontaneous redox reaction.
No. The anode is negative in a galvanic cell but positive in an electrolytic cell. However, oxidation occurs at the anode in both cases.
Electroplating is an electrolytic process. It needs an external battery to deposit metal, so it uses electrical energy to cause a chemical change.
The electrolytic cell converts electrical energy into chemical energy. The galvanic cell does the reverse, converting chemical energy into electrical energy.
Yes. If a reaction runs spontaneously it forms a galvanic cell; running that same reaction backwards by supplying energy makes it an electrolytic process, for example charging a rechargeable battery.
