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Guilherme Mazui

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What is the Difference Between Molar Mass and Molecular Mass?

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The main difference between molar mass and molecular mass lies in what they represent and the units they are measured in:

  • Molar Mass: This refers to the mass of one mole of a substance, including atoms, molecules, or compounds. It is expressed in grams per mole (g/mol) and is numerically equal to the molecular mass.
  • Molecular Mass: This refers to the mass of one molecule of a substance and is measured in atomic mass units (amu). It is defined as the sum of the atomic masses of all the atoms present in a molecule, and it takes into account the presence of isotopes.

Here are some major differences between molar mass and molecular mass:

Difference between Molar Mass and Molecular Mass Molar Mass Molecular Mass
Refers to the mass of one mole of a substance Refers to the mass of one molecule of a substance
Measured in grams per mole (g/mol) Measured in atomic mass units (amu)
Can also be expressed in kilogram per mole Numerically equal to the molecular mass
Not affected by the presence of isotopes Affected by the presence of isotopes

Although the units are different, the numeric measure is the same in both cases when comparing molar mass and molecular mass of the same substance.

On this page
  • What is the Difference Between Molar Mass and Molecular Mass?
  • Comparative Table: Molar Mass vs Molecular Mass

    • Comparative Table: Molar Mass vs Molecular Mass

    Here is a table comparing the differences between molar mass and molecular mass:

    Property Molar Mass Molecular Mass
    Definition The mass of one mole of a substance. The mass of one molecule of a substance, summing the atomic masses of all atoms in the molecule.
    Units Denoted by g/mol (grams per mole). Denoted by Amu (atomic mass units) or Da (Daltons).
    Purpose Used in complex calculations and for measuring the mass of a specific number of entities. Used to compare the masses of different molecules and determine the composition and structure of molecules.
    Accuracy Less accurate compared to molecular mass. Highly accurate and dimensionless.

    In summary, molar mass refers to the mass of one mole of a substance and is used in complex calculations, while molecular mass represents the mass of a single molecule and is used to compare the masses of different molecules and determine their composition and structure. Molar mass is less accurate compared to molecular mass, which is highly accurate and dimensionless.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.