Moles and molar mass are closely related concepts in chemistry, where molar mass is defined as the mass of one mole of a substance.

To elaborate, both moles and molar mass are fundamental to the study of chemistry. A mole is a unit of measurement that quantifies the amount of a chemical substance. It is defined as exactly $6.02214076 \times 10^{23}$ particles, which can include atoms, molecules, ions, or electrons.

Conversely, molar mass refers to the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To calculate molar mass, one sums the atomic masses of all the atoms present in a molecule. For instance, the molar mass of water (H$_2$O) is approximately $18 \, \text{g/mol}$, derived by adding the molar masses of hydrogen ($1 \, \text{g/mol}$ for each of the two hydrogen atoms) and oxygen ($16 \, \text{g/mol}$).

The connection between moles and molar mass is essential in stoichiometry, the branch of chemistry that examines the quantities of substances involved in chemical reactions. Knowing the molar mass of a substance allows for the conversion between the mass of a sample and the number of moles it contains. This relationship is particularly important because chemical reactions occur at the molecular level, while we typically measure substances at a macroscopic level.

For example, if you know the molar mass of a substance, you can determine the number of moles present in a given mass of that substance. Conversely, if you know how many moles you have, you can calculate the total mass. This relationship can be expressed with the formula:

In summary, the relationship between moles and molar mass is a cornerstone of chemistry, enabling us to bridge the macroscopic measurements of grams and kilograms with the microscopic world of atoms and molecules.