Mole (unit) in chemistry as a convenient way to express amounts of reactants and products of chemical reactions. For example, the chemical equation can be interpreted to mean that 2 mol dihydrogen (H) and 1 mol dioxygen (O) react to form 2 mol water (HO). The mole may also be used to represent the number of atoms, ions, or other entities in a given sample of a substance. The concentration of a solution is commonly expressed by its molarity, defined as the amount of dissolved substance per unit volume of solution, for which the unit typically used is moles per litre (mol/l).
Etymology of electricity coulombs, or should we instead use amperes, joules, or watts, or even volts? Physics texts and reference books supply no solid answer, since physicists have gradually abandoned electricity as a scientific term. And yet Quantity of Electricity still persists in its original definition in many major contemporary references. For example, in the modern SI units of physics, the SI definition of coulomb is given as both the unit quantity of electric charge and also the unit quantity of electricity. Encyclopædia Britannica defines the coulomb as the unit quantity of electricity. The Merriam-Webster dictionary, in definition 1a, defines electricity as charge.