The amount of charge in this type of battery can be determined by measuring the density of the electrolyte. Sulfuric acid has a density greater than water. As the battery operates, sulfuric acid is consumed, lowering the density of the electrolyte. The products of the nickel-cadmium cell are all solids that adhere to the electrodes, making the reactions easily reversed during recharging. Corrosion of metals is an electrochemical process.
Corrosion refers to the deterioration of metals.
The most common example is the rusting of iron. A weak electrochemical cell is formed between the metal and some metallic impurities in the presence of water. The iron atoms are oxidized in the presence of water and oxygen and go into solution as ions. The mass of an element produced at an electrode during electrolysis varies directly as the quantity of electricity that is passed through the solution. The quantity of different elements that can be deposited by the same amount of electricity depends on the equivalent masses of these elements.