Question

percent composition and molecular formula
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which information must be known about a compound to find the molecular formula from the empirical formula?
○ density
○ formula mass
○ percent composition
○ mole ratio

Explanation:

The empirical formula gives the simplest whole-number ratio of atoms in a compound. To find the molecular formula (the actual number of each atom in a molecule), you need to know the compound's actual formula mass (molar mass). You calculate the ratio of the molecular formula mass to the empirical formula mass, then multiply each subscript in the empirical formula by this ratio. Density, percent composition, and mole ratio do not provide the necessary mass information to scale the empirical formula to the molecular formula.

Answer:

B. formula mass