AS

The Mole: Fundamental Unit and Calculations

The Mole Concept

Understanding the Mole as a Unit

  • Definition: A mole is a fundamental unit in chemistry, representing a specific number of constituent particles (atoms, molecules, ions, or electrons). This number is known as Avogadro's number.

Avogadro's Number (N_A): Exactly particles per mole. This constant establishes a relationship between the macroscopic world (grams) and the microscopic world (atoms/molecules).

  • Purpose: The mole concept allows chemists to work with precise quantities of substances, enabling calculations for chemical reactions, stoichiometry, and understanding composition.

  • Molar Mass: The mass (in grams) of one mole of a substance. It is numerically equivalent to the atomic mass (for elements) or molecular mass (for compounds) in atomic mass units (amu). For example, the molar mass of carbon (C) is approximately 12.01 \text{ g/mol}, and the molar mass of water (H_2O) is approximately 18.015 \text{ g/mol}.