A 3.585 g sample contains carbon, 1.388 g of h, 1.850 g o, and the molar mass is 62.00 g. what is the molecular formula for this substance?

The question provides the masses of each atom in the molecule. To determine the molecular formula, we must first convert each mass into the amount of moles. However, the numbers are mixed up in the question. The correct values should be:

1.388 g of carbon, 0.3585 g of hydrogen and 1.850 g of oxygen.

1.388 g C / 12.01 g/mol = 0.1156 moles C

0.3585 g H / 1.008 g/mol = 0.3557 moles H

1.850 g O / 15.99 g/mol = 0.1156 moles O

If we divide every value by the lowest number, so 0.1156, we get:

0.1156/0.1156 = 1 C

0.3557/0.1156 = 3 H

0.1156/0.1156 = 1 O

We now have a formula of CH3O. However, this only has a molecular weight of 31 g/mol, but we are told the molecular weight is 62 g/mol. Therefore, we just multiply the number of each atom by 2 giving us the following molecular formula:

C2H6O