Molecular Formula Notes



Molecular Formula Notes

An ionic compound’s formula unit is usually the empirical formula, but a covalent or molecular compound’s formula does not necessarily indicate the actual numbers of atoms present in each molecule.

Steps:

• First, you calculate up the compound’s molar mass from the periodic table.

• Then, you divide the mass they give you in the problem by the molar mass you calculated in the first step

• Finally, you multiply the subscripts in the given formula by the number you calculated in the second step

Examples:

1) The empirical formula of a compound of phosphorus and oxygen is found to be P2O5. Experimentation shows that the molar mass of this compound is 284g/mol. What is the molecular formula?

P2O5=142g 284g=2 Molecular formula is P4O10 because you

142g multiply P2O5 by 2.

2) Determine the molecular formula of a compound with an empirical formula of NH2 and a formula mass of 48g/mol.

NH2=16g 48g=3 Molecular formula is N3H6 because you

16g multiply NH2 by 3.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download