Question

a compound has a molar mass of 134.13 g/mol-1 and the percent composition is 44.77% carbon, 7.52% hydrogen and 47.71% oxygen. what is the molecular formula?

Answer 1

Answer:

Molecular formula = C₅H₁₀O₄

Explanation:

Given data:

Percentage of hydrogen = 7.52%

Percentage of carbon = 44.77%

Percentage of oxygen = 47.71%

Molecular formula = ?

Solution:

Number of gram atoms of H = 7.52 / 1.01 = 7.445

Number of gram atoms of O = 47.71 / 16 = 2.982

Number of gram atoms of C = 44.77/ 12 = 3.731

Atomic ratio:

            C                      :      H                     :         O

           3.731/2.982      :     7.445/2.982    :       2.982/2.982

                1.25              :           2.5              :        1

C : H : O = 1.25 : 2.5 : 1

C : H : O = 4(1.25 : 2.5 : 1 )

Empirical formula is C₅H₁₀O₄

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

Empirical formula mass  = 5×12 + 10×1.01 + 4×16 = 134.1

n = 134.13/ 134.1

n = 1

Molecular formula = n (empirical formula)

Molecular formula = 1 (C₅H₁₀O₄)

Molecular formula = C₅H₁₀O₄