The Difference Between Molecular Mass and Molar Mass
When it comes to chemistry, terms such as molecular mass and molar mass are often used interchangeably. However, they have distinct differences. Both terms are used to describe the weight of a substance, but they refer to different things.
Molecular Mass
Molecular mass refers to the mass of a molecule. It is the sum of the atomic masses of all the atoms in the molecule. Molecular mass is expressed in atomic mass units (amu). The molecular mass is used to determine the stoichiometry of a chemical reaction, which is the quantitative relationship between the reactants and products.
For example, the molecular mass of glucose, which has a chemical formula of C6H12O6, is 180.16 amu. This means that one molecule of glucose weighs 180.16 atomic mass units.
Molar Mass
Molar mass, on the other hand, refers to the mass of one mole of a substance. A mole is a unit of measurement that represents a specific number of molecules, atoms, or ions. One mole of a substance contains Avogadro’s number of particles, which is approximately 6.02 x 10^23 particles.
Molar mass is expressed in grams per mole (g/mol). It is calculated by adding the atomic masses of all the atoms in a molecule. For example, the molar mass of glucose is 180.16 g/mol.
The molar mass is used to convert between the mass of a substance and the number of moles of that substance. This is important for chemical calculations, such as determining the concentration of a solution, or calculating the amount of a substance needed for a reaction.
Conclusion
In summary, molecular mass refers to the weight of a molecule, while molar mass refers to the weight of one mole of a substance. Molecular mass is used to determine the stoichiometry of a chemical reaction, while molar mass is used to convert between the mass of a substance and the number of moles of that substance. While these terms may be similar, it is important to understand their differences in order to properly use them in chemistry.
Table difference between molecular mass and molar mass
| Property | Description |
|---|---|
| Molecular Mass | The mass of a single molecule of a substance |
| Molar Mass | The mass of one mole of a substance |