What is the Difference Between Voltaic Cell and Electrolytic Cell

The key difference between voltaic cell and electrolytic cell is that a voltaic cell uses the energy that is released during a spontaneous redox reaction to generate electricity, whereas an electrolytic cell uses the electrical energy from an external source to force a reaction to occur.

Voltaic cells or galvanic cells and electrolytic cells are two important terms in electrochemistry. Electrochemistry can be described as the study of the relationship between electricity and chemical reactions. There are two types of electrochemical cells; they are voltaic cells and electrolytic cells.

CONTENTS

1. Overview and Key Difference
2. What is a Voltaic Cell 
3. What is an Electrolytic Cell 
4. Voltaic Cell vs Electrolytic Cell in Tabular Form
5. Summary – Voltaic Cell vs Electrolytic Cell 

What is a Voltaic Cell?

A voltaic cell is a type of electrochemical cell that uses spontaneous redox reactions to generate electrical energy. It is also known as a galvanic cell. The cell contains two half-cells that can be either of the same composition or of different compositions. Each half-cell contains an electrode and an electrolyte. The electrode should be immersed in the electrolytic solution. Sometimes, these electrolytes are completely separate, but other times, they are separated only by a porous barrier. When the electrolytes are completely separated, we need to use a salt bridge to maintain the movement of ions between the two electrolytes.

In preparing this cell, we need to consider whether the electrodes and electrolytes are spontaneous or not. We can find it theoretically by calculating the electrode potentials of each half-cell. However, one half-cell should show oxidation, whereas the other half-cell should show a reduction reaction. Oxidation occurs at the anode, whereas reduction occurs at the cathode. Since a galvanic (voltaic) cell uses the energy released during a spontaneous redox reaction to generate electricity, galvanic cells are important as a source of electrical energy. They produce direct current.

What is an Electrolytic Cell?

An electrolytic cell is a device in which electrical energy is converted into chemical energy or vice versa. This type of cell usually contains two metallic or electronic conductors that are held apart from each other and in contact with an electrolyte that is typically dissolved or fused in ionic compounds.

We can use electrolytic cells as electrochemical cells that are used to make electrolysis occur in certain compounds. For E.g. subjecting the water to electrolysis can form gaseous oxygen and gaseous hydrogen. This device uses an electric current to drive thermodynamically unfavored redox reactions. Moreover, oxidation occurs at the anode, while reduction occurs at the cathode.

What is the Difference Between Voltaic Cell and Electrolytic Cell?

The terms voltaic cell (galvanic cell) and electrolytic cell are very important in the production of electricity. The key difference between voltaic cell and electrolytic cell is that a voltaic cell uses the energy that is released during a spontaneous redox reaction to generate electricity, whereas an electrolytic cell uses the electrical energy from an external source to force a reaction to occur. When considering their energy release, voltaic cells derive energy from spontaneous redox reactions, whereas electrolytic cells involve non-spontaneous reactions, and therefore, require external electron sources such as DC batteries of AC power sources.

The following table summarizes the difference between voltaic cell and electrolytic cell.

Summary – Voltaic Cell vs Electrolytic Cell

Voltaic cells and electrolytic cells are two important terms in electrochemistry. The key difference between voltaic cell and electrolytic cell is that a voltaic cell uses the energy that is released during a spontaneous redox reaction to generate electricity, whereas an electrolytic cell uses the electrical energy from an external source to force a reaction to occur.

Reference:

1. “Electrochemistry (Article).” Khan Academy.

Image Courtesy:

1. “Galvanic cell with no cation flow” By Original: Ohiostandard Vector: AntiCompositeNumber – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Electrolytic cell charge” By RodEz2 – Own work (CC BY-SA 3.0) via Commons Wikimedia