Question

The empirical formula of a compound is determined to be CH, and its molecular mass is found to be 78.06 g/mol. Determine the molecular formula of the compound, showing your work.

Answer 1

To find the molecular formula,first we have to divide the molecular mass by the empirical mass.

The empirical mass for the given empirical formula will be:

Mass of carbon (C) + Mass of Hydrogen (H) = 12 + 1 = 13 (roundoff value)

After this, we will divide 78.06g/mol (molecular mass) by 13 (empirical mass) and we will get 6

In the next step, multiply the value (6) to empirical formula and we will have the molecular formula C6H6

Answer 2

1) Find the mass of the empirical formula:

C: 12.011 g/mol

H: 1.008 g/mol
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Mass of the formula CH = 12.011 g/mol + 1.008 g/mol = 13.019 g/mol

Number of times that the mass of the empirical formula is contained in the molar mass = molar mass / mass of the empirical formula

= 78.06 g/ mol / 13.019 g/mol = 6

=> Molecular formula = C6 H6