Question

What is the molecular formula for a compound with a molar mass of 26 g/mol and an empirical formula of CH?

Answer 1

C2H2

To solve this problem, first find the empirical formula mass. Since the empirical formula is CH, the empirical formula mass is C (12 g/mol) + H (1 g/mol) or 13 g/mol.

Then, compare this mass to the molar mass to determine the molecular formula.

So, the molecular formula equals 2 times the empirical formula. The molecular formula is C2H2.

Answer 2

To determine what the molecular formula is simply find the molar mass of the empirical formula, which is about 13 g/mol and take the value of 26 and divide it by 13. This would give a value of 2.

Use this value and multiply the empirical formula atoms to obtain the new molecular formula.

You can always verify if it is the correct formula by finding the molar mass of the molecular formula and checking to see if it equals 26 g/mol.