Govind Sharma
Last Activity: 4 Years ago
moles CO2 = mass / molar mass = 20.47 mg/44.01 g/mol = 0.4651 mmol
moles C = moles CO2 = 0.4651 mmol
mass C = 0.4651 mmol x 12.01 g/mol = 5.586 mg
% mass C = 5.586 mg / 6.51 mg x 100/1 = 85.8 %
moles H2O = 8.36 mg / 18.016 g/mol = 0.4640 mmol
moles H = 2 x moles H2O = 0.9281 mmol
% mass H = 100% - 85.8 % = 14.2 %
% composition
85.8% C, 14.2 % H
ratio moles C : moles H
= 0.4651 : 0.9281
divide each number in the ratio by the smallest number
0.4651 / 0.4651 : 0.9281 / 0.9281
= 1 : 2
empirical formula
CH2
to determine the molecular formula divide the molar mass by the mass of the empirical formula
= 84 g/mol / 14 g/mol
= 6
there are 6 empirical units in the molecular formula
molecular formula = 6 x (CH2)
= C6C12
