Question:medium

What is the molecular formula of a compound that has the empirical formula \( \text{CH}_2\text{O} \) and a molar mass of 90 g/mol?

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To find the molecular formula from the empirical formula, compare the molar mass of the compound with the molar mass of the empirical formula and multiply accordingly.
Updated On: Nov 26, 2025
  • \( \text{C}_3\text{H}_6\text{O}_3 \)
  • \( \text{C}_2\text{H}_4\text{O}_2 \)
  • \( \text{C}_4\text{H}_8\text{O}_4 \)
  • \( \text{C}_3\text{H}_6\text{O}_2 \)
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The Correct Option is A

Solution and Explanation

The empirical formula is \( \text{CH}_2\text{O} \). Its molar mass is calculated as follows:\[\text{Molar mass of } \text{CH}_2\text{O} = 12 + 2(1) + 16 = 30 \, \text{g/mol}\]Comparing the compound's molar mass (90 g/mol) to the empirical formula's molar mass (30 g/mol) yields:\[\frac{\text{Molar mass of compound}}{\text{Molar mass of empirical formula}} = \frac{90}{30} = 3\]This indicates the molecular formula is three times the empirical formula. Consequently, the molecular formula is:\[\text{Molecular formula} = 3 \times \text{CH}_2\text{O} = \text{C}_3\text{H}_6\text{O}_3\]Therefore, the molecular formula of the compound is \( \text{C}_3\text{H}_6\text{O}_3 \).
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