Question

A compound with the empirical formula CH20 was found to have a molar mass between 89g and 91g. What is the molecular formula of the compound?

Answer 1

The molar mass of the Formaldehyde is about 30 gram per mol which means it goes like 90/30 =3. 
So, the molecular formula would be 3 times the empirical formula. C3H6O3.

Answer 2

Answer:

The molecular formula of the compound = $C_3H_{6}O_3$

Explanation:

Given, The empirical formula is = $CH_2O$

Molecular formulas is the actual number of atoms of each element in the compound while empirical formulas is the simplest or reduced ratio of the elements in the compound.

Thus,  

Molecular mass = n × Empirical mass

Where, n is any positive number from 1, 2, 3...

Mass from the Empirical formula = 12 + 2×1 + 16 = 30 g/mol

Also, given that:-

89 g/mol < Molar mass > 91 g/mol

So,  

Molecular mass = n × Empirical mass

89 g/mol < 30 n > 91 g/mol

⇒ n ≅ 3

The molecular formula of the compound = $C_3H_{6}O_3$