What is the difference between molar mass and molecular mass?

1 Answer
May 25, 2016


Discussed below


The molecular mass is a relative mass of a molecule of a substance ( a compound or an element )measured by the ratio of the mass of one molecule of the substance to the mass of #1/12th# part of #""_6^12C# atom.
It is a unitless quantity,being the ratio of two masses.
The tiny constant mass of #1/12th# part of the mass of #"_6^12C# atom is also considered as unit of mass and is known as ‘amu’ or ‘u’.
#1"u or amu"=1.6xx10^(-24)g=1/Ng#
Where N = Avogadro’s Number.

The molecular mass of Carbon dioxide =44
But actual mass of one molecule of carbon dioxide molecule is # 44u#

The molar mass of a substance (a compound or an element) is the mass of 1 mole or Avogadro’s number of the molecules of that substance expressed in #g/(mol)# unit

The molar mass of carbon dioxide is #44g/(mol)#