Final answer:
Molar mass is the mass of one mole of a substance measured in grams per mole, which corresponds to Avogadro's number of particles. It is crucial for converting between mass in grams and the number of moles, making it a fundamental concept in chemical calculations.
Step-by-step explanation:
Molar mass is defined as the mass of one mole of a substance, typically measured in grams per mole (g/mol). The mass of one mole of isotopically pure carbon-12, for instance, is exactly 12 grams, providing a basis for the definition of a mole. Since the molar mass of a substance is the mass of Avogadro's number (6.022 × 1023) of its atoms, molecules, or formula units, it allows chemists to convert between the number of particles in a sample and the mass that can be measured in the laboratory.
For an element, the molar mass is the same as its atomic mass, and for compounds, it corresponds to the molecular or formula mass, all given in grams per mole. Knowing the molar mass of a substance helps chemists calculate the amount of substance in moles when given its mass in grams, and vice versa, which makes it a fundamental concept in chemistry and a crucial conversion factor.