To
determine the molecular formula of the compound given, we first need to
determine the empirical formula. To do that we assume to have 100 grams sample
of the compound with the given composition. Then, we calculate for the number
of moles of each element. We do as follows:
mass
moles ratio
C 85.6 7.13 1
H 14.4 14.26 2
Dividing the number of moles of each element
with the smallest value, we will have the empirical formula:
CH2
To determine the molecular formula, we multiply
a value to the empirical formula. Then, calculate the molar mass and see
whether it is equal to the one given (42.1 g/mol).
molar mass
CH2 14.03
C2H4 28.06
C3H6 42.09
Most likely, the molecular formula of the
compound would be C3H6.
