Question

Determine the molecular formula for the unknown if the molecular mass is 60.0 amu and the empirical formula is ch2o.

Answer 1

Answer:

The molecular formule for this unknow molecule is C2H4O2

Explanation:

The empirical formula is CH2O  ( or better said CnH2nOn)

This means there are 3 elements in the formula of this molecule

⇒ Carbon (C) with a Molar mass of 12 g/mole

⇒ Hydrogen (H) with a Molar mass of 1 g/mole

⇒ Oxygen (O) with a Molar mass of 16 g/mole

We can also notice that the amount of hydrogen should 2x the amount of carbon ( also 2x the amount of oxygen).

The mass of the empirical formule = 12g/ mole + 2* 1 g/mole + 16 g/mole = 30 g/mole

To know what number is n in CnH2nOn we should divide the molecular mass by the empirical mass:

60 g/mole / 30g/mole = 2

this means n = 2

and this will give a molecular formule of C2H4O2  

We can control this to calculate the molecular mass:

2*12 + 4* 1 + 2*16 = 24 + 4 + 32 = 60 g/mole

The molecular formule for this unknow molecule is C2H4O2