Question

Major oil spills are often combatted by applying surfactant formulations such as Corexit. In an effort to determine the empirical formula of 2-BE, the major component of Corexit, a chemist combusts 100.0 g of pure 2-BE. She obtains 223.39 g CO2 and 106.62 g H2O(l). How many moles of carbon is this? how many moles of hydrogen is this? What is the empirical formula of 2-BE? note: analysis shows 2-BE contains only carbon, hydrogen, and oxygen

Answer 1

100.0 g of 2-BE gives 223.39 g CO₂ and 106.62 g water.
The molar masses of CO₂ and water are 44 g/mol and 18 g/mol respectively.
223.39 g of CO₂ corresponds to 223.39/44 = 5.08 moles
106.62 g of water corresponds to 106.62/18 = 5.93 moles of water.
Thus, the number of moles of C present in 100 g of 2-BE is 5.08. This corresponds to 5.08 * 12 = 60.96 g
The number of moles of H present in 100 g of 2-BE is 2 * 5.93 = 11.86. This corresponds to 11.86 * 1 = 11.86 g
Mass of oxygen present in 100 g of 2-BE = 100 - 60.96 - 11.86 = 27.18 g
1 mole of O atoms weighs 16 g.
Moles of oxygen present in 100 g of 2-BE = 27.18/16 = 1.69
The mole ratio C : H : O = 5.08 : 11.86 : 1.69 = 3 : 7 : 1.
Hence, the empirical formula of 2-BE is C₃H₇O.