Key Difference – Active vs Inert Electrodes
An electrochemical cell is composed of two electrical conductors which are called electrodes and an ionic conductor which is called electrolyte. Electrodes transport electrical charge through electrons whereas electrolytes conduct their charge through ions. An electrode is a metal whose surface touches the electrolyte. Electrolyte is a non-metallic component which can be a solution or a vacuum. Ionic compounds cannot conduct electricity in their solid form. Thus, they should be in liquid form in order to conduct electricity. These liquid forms are the electrolytes which were mentioned before. Out of the two electrodes, one acts as the cathode (negatively charged) and other acts as the anode (positively charged). Electrodes are mainly of two types namely, active electrodes and inert electrodes. The key difference between active electrode and inert electrode is that active electrode participates in the chemical reaction whereas inert electrode does not take part in or interfere with the chemical reaction.
CONTENTS
1. Overview and Key Difference
2. What are Active Electrodes
3. What are Inert Electrodes
4. Side by Side Comparison – Active vs Inert Electrodes
5. Summary
What is an Active Electrode?
Active electrode is a metal that is used in electrochemical cells. It participates in reactions that occur in the electrolyte in order to transport the electricity. The active electrode can be oxidized or reduced. Active electrodes are mostly used in electroplating. Electroplating is the process where one metal is applied on another metal with the use of an electrochemical cell. There, the active electrode acts as the anode which provides the cations to the electrolytic solution. Then the cations will reach the cathode and take electrons available there. This causes the deposition of metal ions on the surface of the cathode. Therefore, the material that should be plated by this method is used as the cathode. For example, a spoon can be plated with silver by using a silver anode and the spoon as the cathode; silver nitrate would be the electrolyte.
Basically, active electrode is called “active” because it actively participates in the chemical reaction that occurs in the system. Therefore, it actively exchanges ions with an electrolytic solution. A most commonly used active electrode is the copper electrode.
Figure 01: Copper electrode is an example of an active electrode.
What is an Inert Electrode?
Inert electrode is a metal that does not take part or interfere in any chemical reaction. But it is still used to conduct electricity by transferring electrons with the solution rather than exchanging ions with the solution. Therefore, it serves as an electron. Platinum is used as an inert electrode. But graphite is used widely because it is cheap. Inert electrode may supply or withdraw electrons in the process of conducting electricity. Inert electrodes are always used in electrolysis, the process which separates an ionic compound into its elements. For example, electrolysis of sodium chloride solution produces sodium and chlorine separately.
Figure 02: Graphite electrode is an example of an inert electrode.
What is the difference between Active and Inert Electrodes?
Active vs Inert Electrodes |
|
| Active electrode is the electrode that actively takes part in the chemical reaction of the electrochemical cell. | Inert electrode is an electrode that does not participate in the chemical reaction. |
| Uses | |
| Active electrodes are used in electroplating | Inert electrodes are used in electrolysis. |
| Behavior | |
| Metal ions of active electrode are dissolved in the electrolytic solution | Metal ions of the inert electrode are not dissolved. |
| Reactions | |
| Oxidation or reduction reactions may occur on active electrode | Oxidation or reduction reactions do not occur. |
| Mode of Electrical Conductance | |
| Active electrodes conduct electricity through ion exchange | Inert electrodes conduct electricity through electron transfer. |
Summary – Active vs Inert Electrodes
Electrochemical cells are capable of either generating electrical energy or facilitating electricity through participating in chemical reactions. Basic components of an electrochemical cell are two electrodes and an electrolyte. Two electrodes are named as anode and cathode according to their behavior. Active and inert electrodes are the two types of electrodes. The key difference between active and inert electrode is that active electrode participates in the chemical reaction whereas inert electrode does not take part in or interfere with the chemical reaction.
References:
1. Mittal, V., 2015. Libretexts. [Online] Available at: https://chem.libretexts.org/Core/Analytical_Chemistry/Electrochemistry/Electrolytic_Cells/Electroplating#title[Accessed 26 05 2017].
2.Chang, R., 2010. chemistry. 10th ed. NewYork: McGraw-Hill.
Image Courtesy:
1.”Galvanic cell labeled” By Hazmat2 – Own work (CC BY 3.0) via Commons Wikimedia
2. “Electrolysis of copper chloride solution” by Siyavula Education (CC BY 2.0) via Flickr