Have you ever wondered how batteries work? You know that electric current is created by moving electrons, but what are batteries made of to make that happen? Keep reading to find out! In this article, we'll discuss the Standard Electrode Potential of a species, which includes the reduction potential and oxidation potential. We'll also talk about the oxidation state or oxidation number of a species and what it means for a chemical reaction. Plus, we'll dive into half-reactions or half-cells, redox reactions, and the Galvanic cell. Finally, we'll explain how chemical energy can be turned into electrical energy. By understanding electrode potential, you can get a better grasp on how batteries work and how we can harness energy from chemical reactions. So let's get started!

Standard Electrode Potential

In chemistry, the ability of a species to gain or lose electrons is called Standard Electrode Potential (E°). This potential is measured in volts and represents a species' ability to gain or lose electrons. A species gets oxidized when it loses electrons, and the oxidation state (charge on ion) increases. Conversely, a species gets reduced when it gains electrons, and the oxidation state decreases.

The Standard Electrode Potential for Cu2+ is +0.34 volts, while the reduction potential for Chlorine is +1.36 volts. A species that gains electrons undergoes reduction, and the electrode potential measured for these reactions is called the reduction potential of that species. Conversely, oxidation potential is a measure of the ability of a species to lose electrons and get oxidized in the process. Numerically, oxidation potential is the negative of reduction potential.

The 3 reactions mentioned above (Cu2+, Cl2, V2+) are called half equations, or half cells, and they only show the reduction side of a chemical reaction. However, oxidation and reduction happen simultaneously in a chemical reaction, which is why these reactions are called redox reactions. Generally, half equations are written as reduction equations, and standard electrode potential is written as standard reduction potential. The electrode potential table consists of half reactions of species undergoing reduction and stating the reduction potential of that half reaction. The reduction potential of H+ is the reference point for all other species, and it is considered 0. Electrode potential for all half reactions is measured with reference to H+.

Redox Reactions

When we combine the half-reactions for Copper and Vanadium, we get a redox reaction where Cu2+ gets reduced to Cu, and V gets oxidized to V2+. The net electrode potential of this redox reaction can be used as a battery, called an electrochemical cell. The total E° measured for this cell is called the Electromotive Force or EMF.

Similarly, in the Zinc-Copper battery, the half-reaction for Copper goes in the forward direction (Copper gets reduced) since its E° is positive. This leads to the redox reaction where Zn gets oxidized to Zn2+ and Cu2+ gets reduced to Cu. We can also calculate the E° for this combined redox reaction.

Overall, redox reactions play a crucial role in many chemical reactions and electrochemical cells. By understanding the electrode potential and oxidation states of different species, we can predict which half-reaction will go in the forward direction (reduction) and which will go in the reverse direction (oxidation). This knowledge can be used to design and optimize batteries, fuel cells, and other electrochemical devices. 

Galvanic Cells

A Galvanic Cell is an electrochemical cell that can generate electric current from spontaneous redox reactions. To make a galvanic cell, you will need 2 containers to contain electrolyte of the 2 half reactions, 2 electrodes, a salt bridge, a wire to connect the two electrodes, and a voltmeter to measure the voltage across the cell.

In a Galvanic cell, the electrode at which oxidation takes place is called anode, and the electrode at which reduction takes place is called cathode. Electrons flow from anode to cathode, and current flows from cathode to anode.

The electrode potential is the potential difference between the electrode and the electrolyte in a half cell. The electrode potential is called standard electrode potential when the concentration of all species involved in a half cell is unity.

To measure standard electrode potential, a Standard Hydrogen Electrode (SHE) is used as the reference electrode. In this cell, Hydrogen gas is passed through a tube, and a piece of Platinum serves as the electrical contact and also as a catalyst in the half reaction of Hydrogen. The other half of the galvanic cell consists of the electrode of which the electrode potential has to be measured. The EMF measured for this cell is negative if the electrode undergoing oxidation forms the anode in the cell and the SHE forms the reduction half cell.

Overall, galvanic cells play a crucial role in many applications, including batteries, fuel cells, and electroplating. By understanding the electrode potential and redox reactions, we can design and optimize these electrochemical devices for various practical applications.

Standard electrode potential or standard reduction potential is a measure of the ability of a species to reduce a standard hydrogen electrode at conditions of 298 K, 100 kPa, and 1.00 mol dm−3 ion concentration. It is a measure of the ability of a species to gain or lose electrons.

Reduction potential is the ability of a species to get reduced, while oxidation potential is the negative of reduction potential and is the ability of a species to get oxidized. Species with highly positive reduction potential are good oxidizing agents, while species with highly negative reduction potentials are good reducing agents.

Redox reactions involve both oxidation and reduction reactions taking place in tandem, and each half of a redox reaction is called a half reaction or half cell.

Galvanic cells are electrochemical cells that can convert chemical energy to electrical energy, based on redox reactions. The potential difference between the electrode and the electrolyte is called electrode potential. In a galvanic cell, the electrode where oxidation takes place is called the anode, and the electrode where reduction takes place is called the cathode. Electrons flow from anode to cathode, while current flows from cathode to anode.

Electrode potential for all species is calculated against the Standard Hydrogen Electrode (SHE), which is the reference electrode and its potential is considered to be 0. Standard cell potential, E°, is the difference between the potentials of the reduction half and the oxidation half of a cell, measured at standard conditions of 298 K, 100 kPa, and 1.00 mol dm−3 ion concentration. Overall, understanding electrode potential and redox reactions is crucial in designing and optimizing electrochemical devices for various practical applications. 

Electrode Potential

What is electrode potential?

Electrode potential of a species is the emf generated by a Galvanic cell made from a reference electrode (Hydrogen electrode) and an electrode of the species in question.

How to calculate single electrode potential? 

Single electrode potential for individual species is calculated by measuring the emf generated by a galvanic cell made from an electrode of that species, and a reference electrode (Hydrogen electrode)

What is standard electrode potential?

Standard electrode potential is the electrode potential of a half cell when the concentration of all species involved in the electrolyte is unity.It is also defined as the ability of a species to gain or lose electrons.

What is the formula for electrode potential? 

The net electrode potential of a cell is called emf (electromotive force) (E°cell).E°cell = E°red - E°ox

What are the types of electrode potential? 

Reduction Potential - Ability of a species to get reduced/oxidize other species.Oxidation Potential - Ability of a species to get oxidized/reduce other speciesOxidation potential is the negative of reduction potential.

What is a Galvanic cell?

A Galvanic cell is an electrochemical cell which can convert chemical energy to electrical energy.

‍