Mass relative molecular (Mr)

Mass relative molecular (Mr)
• It is the comparison between the mass of a molecule with a standard.
• The relative molecular mass (Mr) = amount of a substance relative atomic mass (Ar) of the atom-atom molecular oxygen in it.
• Special compound to be used ion term Relative Formula Mass (Mr) because the compound does not consist of ion molecule.
• Mr = Sum of Ar
Example:
Note: relative atomic mass (Ar) H = 1; C = 12, N and O = 14 = 16.
What is the relative molecular mass (Mr) of CO (NH2) 2
Answer:
Mr CO (NH2) 2 = (1 x Ar C) + (1 x Ar O) + (2 x Ar N) + (4 x Ar H)
= (1 x 12) + (1 x 16) + (2 x 14) + (4 x 1)
= 60