Finding the relative formula mass relative molecular mass from a mass spectrum is therefore trivial. Enter any chemical formula optionally with parenthesis and crystal water as in this example. Look for the peak with the highest value for mz and that value is the relative formula mass of the compound.
The relative formula mass of a substance made up of molecules is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.
Answered by Charlotte M. Define relative atomic mass. Relative formula mass is given the symbol Mr. Relative isotopic mass is known to be the relationship between the mass of an isotope of an element relative to the mass of an isotope of the atom.