Question

Both fructose and glucose have an empirical formula of CH2O and a molecular mass of 180.15948 g/mol. Determine the molecular formula.
A)
CH2O


B)
C3H8O3


C)
C6H12O6


D)
C8H16O8

Answer 1

Answer:

C) C₆H₁₂O₆.

Explanation:

• We can determine the molecular formula by calculating the molecular mass of different choices.

Molecular mass = ∑(no. of atoms * atomic mass).

A) CH₂O:

molecular mass = atomic mass of C + 2*atomic mass of H + atomic mass of O = (12.0 g/mol) + (2 * 1.0 g/mol) + (16.0 g/mol) = 30.0 g/mol.

B) C₃H₈O₃:

molecular mass = 3(atomic mass of C) + 8(atomic mass of H) + 3(atomic mass of O) = 3(12.0 g/mol) + 8(1.0 g/mol) + 3(16.0 g/mol) = 92.0 g/mol.

C) C₆H₁₂O₆:

molecular mass = 6(atomic mass of C) + 12(atomic mass of H) + 6(atomic mass of O) = 6(12.0 g/mol) + 12(1.0 g/mol) + 6(16.0 g/mol) = 180.0 g/mol.

D) C₈H₁₆O₈:

molecular mass = 8(atomic mass of C) + 16(atomic mass of H) + 8(atomic mass of O) = 8(12.0 g/mol) + 16(1.0 g/mol) + 8(16.0 g/mol) = 240.0 g/mol.

So, the right choice is: C) C₆H₁₂O₆.