Empirical and Molecular Formulas

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What is an empirical formula?

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An empirical formula represents the simplest whole-number ratio of atoms of each element in a compound.

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How do you calculate the empirical formula from percent composition?

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1. Convert percentages to grams. 2. Convert grams to moles. 3. Divide by the smallest number of moles to find the ratio.

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What is a molecular formula?

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A molecular formula shows the actual number of atoms of each element in a molecule of a compound.

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How do you determine the molecular formula from the empirical formula?

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1. Calculate the molar mass of the empirical formula. 2. Divide the molar mass of the compound by the empirical formula mass. 3. Multiply the subscripts in the empirical formula by this ratio.

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What is the empirical formula for a compound with 72.2% magnesium and 27.8% nitrogen?

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Mg3N2

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What is the molecular formula for glycerol with a molar mass of 92.09 g/mol and percent composition of 39.12% C, 8.75% H, and 51.12% O?

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C3H8O3

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Which pair has the same empirical formula: NaCrO4 and Na2Cr2O7, or C2H4O2 and C6H12O6?

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C2H4O2 and C6H12O6

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What is the empirical formula for a compound with 40.05% sulfur and 59.95% oxygen?

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SO3

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How do you find the empirical formula from a given mass of elements?

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1. Convert mass to moles. 2. Find the simplest mole ratio. 3. Write the empirical formula using the ratio.

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What is the significance of the empirical formula in chemistry?

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The empirical formula provides essential information about the composition of a compound, which is useful for understanding its properties and reactions.