Difference Between Single Electrode Potential and Standard Electrode Potential

The key difference between single electrode potential and standard electrode potential is that single electrode potential is the potential of a single electrode in an electrochemical cell whereas standard electrode potential is the potential difference between two electrodes at standard conditions.

An electrochemical cell is a device that can either generate electricity using chemical reactions or use electricity to cause chemical reactions. It has two electrodes as cathode and anode. Each electrode is named as a half cell, where a half reaction of a redox reaction takes place. Electricity is generated due to the electric potential between two electrodes. If we consider the potential of a half cell, we call it “single electrode potential”. We cannot measure it, and it is always measured compared to the potential of the other electrode.

CONTENTS

1. Overview and Key Difference
2. What is Single Electrode Potential 
3. What is Standard Electrode Potential 
4. Side by Side Comparison – Single Electrode Potential vs Standard Electrode Potential in Tabular Form
5. Summary

What is Single Electrode Potential?

Single electrode potential is the potential of a half cell of an electrochemical cell. An electrochemical cell contains two half cells. Generally, each half cell is a metal electrode. These metals release their ions into the electrolyte (the solution in which the electrodes are immersed) if there is an open circuit. Therefore, this electrode can develop an electric potential around itself. Thus, it is what we call as a single electrode potential.

For example, in a Daniel cell, the anode is Zinc, and the cathode is copper. Here, the anode develops a negative charge while the cathode develops a positive charge. These charges individually determine the single electrode potential of these electrodes. Furthermore, there are three factors on which this potential depends on; concentration of ions in the solution, tendency to form ions and temperature.

What is Standard Electrode Potential

Standard electrode potential is the potential of a half cell at standard conditions. In an electrochemical cell, the electricity is generated as a result of the potential difference between two electrodes. There is no way to measure the electrode potential simply and accurately. Moreover, it varies with temperature, concentration and pressure of the system. Therefore, we need to define a standard electrode potential.

The standard electrode potential is the potential of an electrode at 1-atmosphere pressure, 25°C temperature and 1M molar concentration of ions in the electrolyte. Since we cannot measure the individual electrode potential, we measure this standard value against standard hydrogen electrode potential.

What is the Difference Between Single Electrode Potential and Standard Electrode Potential?

An electrochemical cell contains two electrodes known as half cells. The electric potential of one electrode is a single electrode potential. However, if we measure it at standard conditions, then we call it standard electrode potential. Hence, the key difference between single electrode potential and standard electrode potential is that single electrode potential is the potential of a single electrode in an electrochemical cell whereas standard electrode potential is the potential difference between two electrodes at standard conditions. Moreover, the standard conditions are standard hydrogen electrode potential.

The below infographic shows more details on the difference between single electrode potential and standard electrode potential.

Summary – Single Electrode Potential vs Standard Electrode Potential

An electrochemical cell contains two electrodes. We call the potential of on electrode “single electrode potential”. The key difference between single electrode potential and standard electrode potential is that the single electrode potential is the potential of a single electrode in an electrochemical cell whereas standard electrode potential is the potential difference between two electrodes at standard conditions.

Reference:

1. “Standard Electrode Potentials.” Standard Electrode Potentials, Available here.
2. “Single Electrode Potential.” BrainKart, Available here.

Image Courtesy:

1. “Daniel cell” By Kurzon at English Wikipedia – Transferred from en.wikipedia to Commons by Armando-Martin using CommonsHelper (Public Domain) via Commons Wikimedia
2. “Standard electrode potential of zinc” By Andyrendall – Own work (Public Domain) via Commons Wikimedia