Question

What is meant by molar mass?

Answer 1

Generally mass of the substance or a compound is different from the molar mass of the substance. One mole of a molecule is equal to the Avogadro number of atoms or molecules present in the compound.

Complete Solution :
- In the question it is asked what is meant by molar mass.
- Molar mass is the mass of one mole of a given compound or substance.
- We know that the number moles of a compound (n) are the ratio of given mass of the compound to the molar mass of the compound and can be expressed as follows.
$\text{Number of moles (n) =}\dfrac{\text{Given mass (m)}}{\text{Molar mass (M)}}$

- We can write the above formula in the following way to get the molar mass (m) of the compound.
$\text{Molar mass (M) = Mass(m) }\\!\\!\times\\!\\!\text{ number of moles (n)}$
- Means molar mass (M) is the product of mass (m) of the compound and number of moles (n) of the given compound.
- The unit to measure the mass of the compound is gram.
- The unit to measure the molar mass of the compound is grams per mole or g/mol.

Note: Don’t be confused with the words molar mass and molecular weight of the substance. Both are not the same. Mass of compound is the sum of atomic weight of each atom present in the given molecule but the molar mass means is the product of molecular weight and the number of moles of the given compound.
- Molecular weight of the sodium hydroxide is 40 g. and the molar mass of the sodium hydroxide is 40 g/mol.