- Empirical Formula of a compound shows the ratio of elements present in a compound.
- Molecular Formula of a compound shows how many atoms of each element are present in a molecule of the compound.
- The empirical formula mass of a compound refers to the sum of the atomic masses of the elements present in the empirical formula.
- The relative molecular mass (formula mass, formula weight or molecular weight) of a compound is a multiple of the empirical formula mass.
RMM = n x empirical formula mass
- Empirical Formula can be calculated from the percentage (or percent) composition of a compound.
- The molecular formula for water is H2O, a 2 to 1 ratio.
Since the subscripts will not reduce H2O is also water's empirical formula.
- The molecular formula for hydrogen peroxide is H2O2, a 1 to 1 ratio.
The formula is correct. Remember that peroxide is a polyatomic ion with a charge of -2.Reduce the subscripts to the lowest form.
The empirical formula for hydrogen peroxide is HO, a 1 to 1 ratio.
- Subscripts in a chemical formula are usually thought of as a ratio of atoms.
Subscripts can also be thought of as a ratio of moles . . . . .
a mole being the number of atoms needed
to equal the atomic mass number of an element.
To determine an empirical formula, one must determine the mole ratio.