Given that the empirical formula is HO and the molar mass is 34.02 g/mol, what is the molecular formula of the compound?

• A. H2O
• B. H2O2
• C. HO
• D. H2O4

Answer: (B)

Verified step by step guidance

1. Determine the molar mass of the empirical formula HO by adding the atomic masses of hydrogen (H) and oxygen (O). Use the atomic masses: H = 1.01 g/mol, O = 16.00 g/mol. Calculate the empirical formula mass as \$1.01 + 16.00$ g/mol.
2. Calculate the ratio of the given molar mass of the compound (34.02 g/mol) to the empirical formula mass found in step 1. This ratio tells you how many empirical units are in the molecular formula. Use the formula: \(\text{ratio} = \frac{\text{molar mass}}{\text{empirical formula mass}}\).
3. Determine the integer closest to the ratio calculated in step 2. This integer represents the number of empirical formula units in the molecular formula.
4. Multiply each subscript in the empirical formula HO by the integer found in step 3 to get the molecular formula. For example, if the integer is 2, multiply H and O by 2 to get \(\mathrm{H_2O_2}\).
5. Write the molecular formula using the new subscripts and verify that its molar mass matches the given molar mass (34.02 g/mol) by recalculating the total mass.