PPT Slide

Molecular Formulas

19

• The actual number of moles of each element in the smallest unit  of the compound.

• In water (H 2O), ammonia (NH 3), methane (CH 4), and ionic  compounds, the empirical and molecular formulas are identical.

• In some cases the molecular formula is a whole-number multiple of the empirical formula.

• Using the empirical formula to obtain the molecular formula.

Hydrogen peroxide has the empirical formula HO (17.01g/mol)

Dividing its molar mass (34.02 g/mol) by the empirical formula mass gives the whole-number multiple:

The molecular formula is H 2O2 .

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