The key difference between electrochemical cell and galvanic cell is that most electrochemical cells tend to convert electrical energy into chemical energy, whereas galvanic cells tend to convert chemical energy into electrical energy.
Oxidation and reduction reactions play an important role in electrochemistry. In an oxidation-reduction reaction, electrons are transferred from one reactant to another. The substance that accepts electrons is the reducing agent, whereas the substance which gives away the electron is the oxidizing agent. The reducing agent is responsible for reducing the other reactant while undergoing oxidation itself; for the oxidizing agent, this is vice versa. These reactions occur in two half-reactions to show separate oxidations and reductions; thus, it shows the number of electrons moving in or out.
CONTENTS
1. Overview and Key Difference
2. What is an Electrochemical Cell
3. What is a Galvanic Cell
4. Side by Side Comparison – Electrochemical Cell vs Galvanic Cell in Tabular Form
5. Summary
What is an Electrochemical Cell?
An electrochemical cell is a combination of a reducing and oxidizing agent, which are physically separated from each other. Usually, we do this separation by a salt bridge. Although they are physically separated, both half-cells are in chemical contact with each other. Electrolytic and galvanic cells are two types of electrochemical cells.
Oxidation-reduction reactions take place in both electrolytic and galvanic cells. Therefore, in an electrochemical cell, there are two electrodes as an anode and a cathode. Both electrodes externally connect with a high resistant voltmeter; therefore, current there is not transmitting between the electrodes. Therefore, this voltmeter helps to maintain a certain voltage between the electrodes where oxidation reactions take place.
Figure 01: Electrochemical Cell
Oxidation reaction takes place on the anode, while the reduction reaction takes place on the cathode. We need to immerse them in separate electrolyte solutions. Normally, these solutions are ionic solutions related to the type of electrode. For example, we immerse copper electrodes in a copper sulfate solution and silver electrodes in a silver chloride solution. These solutions are different; hence, they have to be separated. The most common way to separate them is a salt bridge. In an electrochemical cell, the potential energy of the cell converts to an electrical current, which we can use to light a bulb or to do some other electrical work.
What is a Galvanic Cell?
Galvanic or voltaic cells store electrical energy. Batteries are made from a series of galvanic cells to produce a higher voltage. The reactions at the two electrodes in Galvanic cells tend to proceed spontaneously. When the reactions take place, there is a flow of electrons from the anode to the cathode via an external conductor.
Figure 02: A Galvanic Cell
For example, if the two electrodes are silver and copper in a Galvanic cell, the silver electrode is positive with respect to the copper electrode. The copper electrode is the anode, and it undergoes oxidation reaction and releases electrons. These electrons go to the silver cathode via the external circuit. Hence, silver cathode undergoes reduction reaction. A potential difference is generated between the two electrodes, which allow the electron flow. Following is the spontaneous cell reaction of the above Galvanic cell.
2 Ag+ (aq) + Cu(s) ⇌ 2Ag (s) + Cu2+ (aq)
What is the Difference Between Electrochemical Cell and Galvanic Cell?
There are two types of electrochemical cells as electrolytic cells and galvanic cells. The key difference between electrochemical cell and galvanic cell is that most electrochemical cells tend to convert electrical energy into chemical energy, whereas galvanic cells tend to convert chemical energy into electrical energy. Furthermore, in most electrochemical cells such as electrolytic cells, the anode is the positive terminal while the cathode is the negative terminal; however, in the galvanic cell, the anode is the negative terminal and cathode is the positive terminal.
Moreover, a further difference between electrochemical cell and galvanic cell is that in electrochemical cells, such as electrolytic cells, non-spontaneous chemical reactions take place, but in galvanic cells, spontaneous chemical reactions take place.
Summary – Electrochemical vs and Galvanic Cell
There are two types of electrochemical cells as electrolytic cells and galvanic cells. The key difference between electrochemical cell and galvanic cell is that most electrochemical cells tend to convert electrical energy into chemical energy, whereas galvanic cells tend to convert chemical energy into electrical energy.
Reference:
1.“Electrochemical Cell.” Electrochemical Cell – an Overview | ScienceDirect Topics, Available here.
Image Courtesy:
1. “ElectrochemCel” By Alksub at the English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “Galvanic Cell” By Gringer – File:Galvanische Zelle.png, by Tinux (CC BY-SA 3.0) via Commons Wikimedia