Question

Select the correct answer.
A compound is used as a food additive. The compound has a molar mass of 176.124 grams/mole. A 692.5-gram sample undergoes
decomposition, producing 283.4 grams of carbon, 31.7 grams of hydrogen, and 377.4 grams of oxygen. What is the molecular formula of the
compound?

Answer 1

Answer:

Molecular formula =  C₆H₁₂O₆

Explanation:

Given data:

Mass of hydrogen = 31.7 g

Mass of carbon = 283.4 g

Mass of oxygen = 377.4 g

Molar mass of compound = 176.124 g/mol

Molecular formula = ?

Solution:

Number of gram atoms of H = 31.7 / 1.01 = 31.4

Number of gram atoms of O = 377.4 / 16 = 23.6

Number of gram atoms of C = 283.4 / 12 = 23.6

Atomic ratio:

            C                      :      H                 :         O

           23.6/23.6         :     31.4/23.6     :       23.6/23.6

              1                      :        1.33              :        1

C : H : O =3 (1 : 1.33 : 1 )

Empirical formula is C₃H₄O₃.

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

Empirical formula mass  = 3×12+4+3×16 = 88

n = 176.124 / 88

n = 12

Molecular formula = n (empirical formula)

Molecular formula = 2 (C₃H₄O₃)

Molecular formula =  C₆H₁₂O₆