A compound has an empirical formula of C2H6O and a molar mass of 138 g/mole. Determine its molecular formula.
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Answer: B. C6H18O3
Explanation
The empirical formula mass of carbon two hydrogen six oxygen is calculated as forty-six grams per mole. Dividing the given molar mass of one hundred thirty-eight by forty-six gives a whole number multiplier of three. Multiplying each subscript in the empirical formula by three yields the correct molecular formula. Empirical formulas show the simplest whole-number ratio of atoms present in a chemical compound. Molecular formulas express the actual number of atoms of each element in a single molecule. Molar mass determinations often require analytical techniques like mass spectrometry or freezing point depression.
Organic chemists determine empirical and molecular formulas to characterize newly synthesized compounds. Pharmaceutical research depends on exact molecular formulas to verify drug purity and chemical structure. Combustion analysis data allows scientists to calculate empirical formulas for unknown organic substances. Option A represents the empirical formula rather than the larger required molecular formula. Option C has an incorrect atomic ratio that does not match the given molar mass value. Option D represents a different chemical formula with a much smaller molar mass than specified.
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