Half-cells are constructed by dipping an electrode into an electrolyte, where the electrode may or may not take part in the reaction
In the Gas/Non-metal ion half-cell, oxidation potential and reduction potential are relative tendencies, for example, Copper can act as cathode or anode depending on the elements involved
Standard Electrode Potential (E0) is a measurement of the tendency of a half-cell reaction to occur as a reduction reaction, with potential difference measured in Volts
The Standard Hydrogen Electrode (SHE) is connected to different half-cells, and the electrochemical series is based on the relative Standard Reduction Potentials (SRP) values
To predict the operation of a galvanic cell, the electrochemical series is used to identify the anode and cathode, and determine the direction of electron flow
The maximum potential difference of a cell under standard conditions is the difference between the E° values of its two half-cells, and different values for the cell voltage are obtained under non-standard conditions
As a galvanic cell discharges, the cell voltage eventually drops to zero, reaching equilibrium, referred to as 'flat'
The Electrochemical Series can predict the likelihood of a redox reaction taking place when different chemicals are combined, ranking the relative strengths of oxidising and reducing agents
For a spontaneous reaction to occur, an oxidising agent on the left of the electrochemical series must react with a reducing agent on the right that is lower in the electrochemical series
Rechargeable cells, also known as secondary cells or accumulators, like lithium-ion cells and nickel–metal hydride cells, can be recharged by reversing the cell reaction with a charger
During recharging, the cell reaction is reversed, converting the products back into the original reactants, and during discharging, the cell acts as a Galvanic cell
Battery life of secondary cells decreases over time due to side reactions that reduce the amount of active material in a battery, with self-discharge occurring when not in use