Answer to Question #348756 in General Chemistry for Semere

Question

Determine the molecular formula of a compound having a simplest formula of CH

and formula mass of 78.

Answer 1

Solution:

Simplest formula mass of CH = A_r(C) + A_r(H) = 12 + 1 = 13 g mol⁻¹

Molecular formula mass of compound = 78 g mol⁻¹

Molecular formula mass / Simplest formula mass = n formula units/molecule

(78 g mol⁻¹) / (13 g mol⁻¹) = 6 formula units/molecule

 

Finally, derive the molecular formula of the compound from the simplest formula by multiplying each subscript by six: (CH)₆ = C₆H₆

Therefore, the molecular formula of the compound is C₆H₆

Answer: The molecular formula of the compound is C₆H₆