Which Statement Best Describes a Mole?

Which statement best describes a mole?

A. It is used mainly for writing chemical formulas.

B. It is used for chemical equations that have reversible reactions.

C. It is used for directly comparing the amounts of substances.

D. It is used mainly for dealing with fluid substances.

Ans. C. It is used for directly comparing the amounts of substances.

A mole is the SI unit of the quantity of substance, and its magnitude, Avogadro's number (6.022×1023), is the number of particles (atoms, molecules, ions, etc.) in a given amount of that substance. This simple concept allows chemists to equate values of different substances on a particle-to-particle basis, regardless of their mass or volume. This is crucial in stoichiometry, where chemical equations are balanced in moles of reactants and products. The mole spans the microscopic world of atoms and molecules and the macroscopic world of laboratory measurement.