Question

what is the molecular mass

Answer 1

Relative Molecular mass or molecular weight is the mass of a molecule. It is calculated as the sum of the atomic weights of each constituent element multiplied by the number of atoms of that element in the molecular formula. 

Answer 2

The Definition:

Mass of a molecule is how many times it is greater than 1 / 12th mass of one atom of a Carbon 12 isotope.

The Formula of Molecular Mass:

$\boxed{Molecular Mass = \frac{Mass of a molecule in amu}{1/12th mass of 1 atom of C 12 = 1 amu} }$

Molecular Mass of methane in u(atomic mass Units)

CH4 = 12.01u + 4 x 1.008 u  = 16.048 u

Atomic mass, molecular mass are represented in grams. This known as gram atomic mass and gram molecular mass  respectively.

This is represented as GAM and GMM

Formula mass is not the same as molecular mass.