An unknown acid has a molar mass of 60.06 g/mol.Given the following percent composition,what is the molecular formula?
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Question

An unknown acid has a molar mass of 60.06 g/mol.Given the following percent composition,what is the molecular formula? 
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Quizplus · Accepted Answer

First, we need to find the empirical formula by converting the percentages into moles: C: 52.03% = 52.03 g / 12.01 g/mol = 4.33 mol H: 6.72% = 6.72 g / 1.01 g/mol = 6.64 mol S: 27.95% = 27.95 g / 32.07 g/mol = 0.87 mol O: 13.30% = 13.30 g / 16.00 g/mol = 0.83 mol Next, we need to divide each mole value by the smallest value to get the empirical formula: C: 4.33 mol / 0.83 mol = 5.21 ≈ 5 H: 6.64 mol / 0.83 mol = 8.00 ≈ 8 S: 0.87 mol / 0.83 mol = 1.05 ≈ 1 O: 0.83 mol / 0.83 mol = 1.00 ≈ 1 The empirical formula is C5H8SO, and we can calculate its molar mass: (5 x 12.01) + (8 x 1.01) + 32.07 + 16.00 = 120.18 g/mol Finally, we can calculate the molecular formula by dividing the given molar mass by the empirical formula mass: molecular formula mass / empirical formula mass = n 60.06 g/mol / 120.18 g/mol = 0.499 n ≈ 0.5 Then, we can multiply the empirical formula by n to get the molecular formula: C5H8SO x 0.5 = C10H16SO The molecular formula is C₂H₄O₂.

An Unknown Acid Has a Molar Mass of 60