The mass of a mole of atoms, also known as the molar mass, is used as a reference instead of the mass of a single atom for several reasons:
Practicality: The mass of a mole of atoms is a more convenient quantity to work with in chemical calculations. It allows for easier comparisons of different elements and compounds and simplifies calculations involving large quantities of atoms or molecules.
Consistency: The molar mass allows for consistent comparisons between different elements. It provides a standard unit for comparing masses, regardless of the element's atomic number or the number of atoms involved.
Avogadro's Principle: The concept of the mole is based on Avogadro's principle, which states that equal volumes of gases at the same temperature and pressure contain an equal number of particles (atoms, molecules, or ions). The molar mass is directly related to this principle, as one mole of any substance contains Avogadro's number (6.022 × 10^23) of particles. This relationship simplifies stoichiometric calculations and allows for the conversion between mass and the number of particles.
Chemical Reactions: Molar masses are crucial for balancing chemical equations and determining the stoichiometry of reactions. By comparing the molar masses of reactants and products, it becomes possible to calculate the masses of substances involved in a reaction and predict the quantities needed or produced.
In summary, using the mass of a mole of atoms as a reference provides a practical and consistent way to compare and calculate quantities in chemistry. It simplifies calculations, allows for the use of Avogadro's principle, and facilitates the understanding of stoichiometry in chemical reactions.