Question

Define the term Relative molecular mass. State why indirect methods are utilised to determine the absolute mass of an atom. Explain in brief the indirect method used.

Answer 1

Relative molecular mass [RMM] of an element/compound : “Is the number of times one molecule of the substance is heavier than 1/12 the mass of an atom of carbon [C¹²].

RAM = `"Mass of one atom of the element"/("Mass of one atom of carbon"["C"^12])`

OR

“Mass of one molecule as compared with the 1/12 mass of an atom of carbon[C¹²]”

RMM = `("Mass of one molecule of the substance")/((1/2) "Mass of one atom of carbon"["C"^12])`

To determine the absolute mass of an atom indirect methods are utilised as Atom are extremely small and very light.
An isotope of carbon C¹² [carbon -12 atom] has been assigned an atomic mass of exactly 12 atomic mass units] is used.