A molecule has the empirical formula C4H6O. If its molecular weight is determined to be about 212 g/mol, what is the most likely molecular formula?

a. C12H18O3
b. C8H12O3
c. C11H16O4
d. C4H6O
e. C2H3O

The molecular formula is C12H18O3

Explanation:

Step 1: Data given

The empirical formula is C4H6O

Molecular weight is 212 g/mol

atomic mass of C = 12 g/mol

atomic mass of H = 1 g/mol

atomic mass of O = 16 g/mol

Step 2: Calculate the molar mass of the empirical formula

Molar mass = 4* 12 + 6*1 +16

Molar mass = 70 g/mol

Step 3: Calculate the molecular formula

We have to multiply the empirical formula by n

n = the molecular weight of the empirical formula / the molecular weight of the molecular formula

n = 70 /212 ≈ 3

We have to multiply the empirical formula by 3

3*(C4H6O- = C12H18O3

The molecular formula is C12H18O3

The molecular formula is most likely to be first option, .

Explanation:

Both the molecular formula and the empirical formula of a molecule give the types of atoms in that molecule. However, the molecular formula of a molecule gives the exact number of atoms each molecule. On the other hand, the empirical formula gives only a simplified ratio.

For example, if the empirical formula of the molecule is , then the molecular formula would be , or equivalently , where is a positive whole number (, etc.) The goal here is to find the value of

Look up the relative atomic mass data on a modern periodic table:

The formula mass of would be

.

The formula mass of would be

.

On the other hand, since the molecule should have a molecular mass of ,

.

. (Round to the nearest whole number.)

Hence, the molecular formula would be , which simplifies to .

increased stability in the completion of fluorine's outer shell.