"Molecular weight" and "molar mass" are related terms used in the field of chemistry, but they refer to slightly different concepts.
Molecular Weight: Molecular weight is a term commonly used in the context of organic and inorganic chemistry to describe the mass of a single molecule of a substance relative to the unified atomic mass unit (u). It is also known as the molecular mass. Molecular weight is calculated by summing up the atomic masses of all the atoms in a molecule. The unit of molecular weight is usually expressed in atomic mass units (amu) or grams per mole (g/mol). It provides information about the mass of a specific molecule, regardless of the amount of substance present.
Molar Mass: Molar mass, on the other hand, is a property of a substance and is defined as the mass of one mole of that substance. It is essentially the mass of a given substance divided by its amount in moles. The unit of molar mass is also expressed in grams per mole (g/mol). Molar mass can be calculated by summing up the atomic masses of all the atoms in a formula unit or a molecule. It is used to convert between the mass of a substance and the number of moles present.
In summary, the main difference between molecular weight and molar mass lies in their usage. Molecular weight refers to the mass of a single molecule, while molar mass represents the mass of one mole of a substance. Molecular weight is molecule-specific, whereas molar mass is a characteristic property of a substance.