Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO₂and 0.226 g H₂O. What is its empirical formula? A)C ₂H ₃O ₄ B)C ₃H ₄O ₂ C)C ₄H ₃O ₂ D)C ₅H ₁₂O ₄ E)C ₂H ₂O

Question

Quizplus · Accepted Answer

To find the empirical formula, we first need to calculate the moles of each element in the compound.
moles of CO2 = 1.471 g / 44.01 g/mol = 0.0334 mol
moles of H2O = 0.226 g / 18.015 g/mol = 0.0126 mol
Using the mole ratio, we divide the moles of each element by the smallest number of moles to get the subscripts for the empirical formula.
C: 0.0334 mol / 0.0126 mol = 2.65 ≈ 3
H: 0.0126 mol / 0.0126 mol = 1
O: 0.0126 mol / 0.0126 mol = 1
Therefore, the empirical formula is C3H1O1, which simplifies to C3H1O or C3H1. This choice is only given in option C.

Terephthalic Acid, Used in the Production of Polyester Fibers and Films