The molecular formula is D. C_8H_20O_4Si.
Step 1.Calculate the empirical formula
a) Calculate the moles of each element
Moles of C= 196.01 g C × (1 mol C/12.01 g C) = 16.325 mol C
Moles of H = 41.14 g H × (1 mol H/1.008 g H) = 40.813 mol H
Moles of O = 130.56 g O × (1 mol O/16.00 g O) = 8.1650 mol O
Moles of Si = 57.29 g Si × (1 mol Si/28.085 g Si) = 2.0399 mol Si
b) Calculate the molar ratio of each element
Divide each number by the smallest number of moles and round off to an integer
C:H:O:Si = 8.0027:20.008:4.0027:1 ≈ 8:20:4:1
c) Write the empirical formula
EF = C_8H_20O_4Si
Step 2. Calculate the molecular formula
EF Mass = 208.33 u
MF mass = 208.329 u
MF = (EF)_n
n = MF Mass/EF Mass = 208.329 u/208.33 u = 1.0000 ≈ 1
MF = C_8H_20O_4Si
