Question

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?

• A. \( \text{C}_3\text{H}_6\text{O}_3 \)
• B. \( \text{C}_2\text{H}_4\text{O}_2 \)
• C. \( \text{C}_4\text{H}_8\text{O}_4 \)
• D. \( \text{C}_3\text{H}_6\text{O}_2 \)

Hint:

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.

Answer 1

The Correct Option is A

The empirical formula is \( \text{CH}_2\text{O} \), which has a molar mass of: \[ \text{Molar mass of } \text{CH}_2\text{O} = 12 + 2(1) + 16 = 30 \, \text{g/mol} \] Now, compare the molar mass of the compound (90 g/mol) to the molar mass of the empirical formula (30 g/mol): \[ \frac{\text{Molar mass of compound}}{\text{Molar mass of empirical formula}} = \frac{90}{30} = 3 \] This means the molecular formula is 3 times the empirical formula. Therefore, the molecular formula is: \[ \text{Molecular formula} = 3 \times \text{CH}_2\text{O} = \text{C}_3\text{H}_6\text{O}_3 \] Thus, the molecular formula of the compound is \( \text{C}_3\text{H}_6\text{O}_3 \).