How are the molecular mass and molar mass of a compound similar and how are they different?

Similarities: both state the mass of chemical species and they have the same numerical value

Differences: molecular mass refers to one single molecule and molar mass refers to one mole of a molecule

Explanation:

The molecular mass is the value of the mass of each molecule and it is measured in mass units (u). It is calculated adding the mass of each atom of the molecule.

The molar mass is the value of the mass of one mole of molecules, which means the mass of 6.022140857 × 10²³ molecules. The unit is g/mol.

For example, we can consider the methane molecule, which has the chemical formula of CH₄:

Molecular mass CH₄ = C mass + 4 x (H mass)

Molecular mass CH₄ = 12.01 + 4 x (1.01)

Molecular mass CH₄ = 16.05 u

Now to calculate the molar mass we multiply the value of the molecular mass by the Avogadro number and convert the units to g/mol:

Molar mass CH₄: 16.05 x x 6.022140857 × 10²³ mol⁻¹

Molecular mass CH₄ = 16.05 g / mol