12/4-5 Exit Ticket: 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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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 calculate percent composition?

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Percent composition is calculated by dividing the mass of each element in a compound by the total molar mass of the compound, then multiplying by 100.

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What is the relationship between empirical and molecular formulas?

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The molecular formula is a whole-number multiple of the empirical formula.

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How do you determine the empirical formula from percent composition?

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Convert the percent composition to grams, then to moles, and find the simplest mole ratio.

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What is the molar mass of a compound?

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The molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol).

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If the empirical formula is CH2O, how do you find the molecular formula given the molar mass?

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Divide the molar mass of the compound by the molar mass of the empirical formula to find the multiplier, then multiply the subscripts in the empirical formula by this number.

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What is the empirical formula for a compound with 40.05% S and 59.95% O?

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SO3.

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What is the empirical formula for a compound with 72.2% Mg and 27.8% N?

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Mg3N2.

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How do you convert grams to moles?

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To convert grams to moles, divide the mass of the substance by its molar mass.