A compound having an empirical formula of C_3H_4O_3C3H4O3 has a mass of 180 g/mol. What is the molecular formula?

1 Answer
Jun 4, 2016

"Molecular formula"Molecular formula == C_6H_8O_6C6H8O6

Explanation:

The molecular formula is always a whole number multiple of the empirical formula:

i.e. "Molecular formula"Molecular formula == "(Empirical formula)"xxn(Empirical formula)×n

So we need to solve for nn.

Thus 180*g*mol^-1180gmol1 == nxx(3xx12.011+4xx1.0079+3xx15.999)*g*mol^-1n×(3×12.011+4×1.0079+3×15.999)gmol1
== nxx(88.0)*g*mol^-1n×(88.0)gmol1

n~=2n2. Thus "Molecular formula"Molecular formula == C_6H_8O_6C6H8O6.

Of course, the ratio is out a little bit. Such errors are common in the determination of such formulae.