Question

N-Butyl phthalate, used as an insect repellent, consists of carbon, hydrogen, and oxygen. In a combustion analysis of a 0.3413 g sample, 0.2430 g of water and 0.8633 g of carbon dioxide were produced. The molecular weight is 278.38 g/mol. Calculate the empirical formula and molecular formula. Highlight the key steps discussed in class to solve this problem, including any stoichiometry involved.

a) C₄H₆O₄, C₈H₁2O₈
b) C₂H₃O₂, C₄H₆O₄
c) C₃H₅O₃, C₆H₁0O₆
d) C₅H₇O₅, C₁0H₁4O₁0

Answer 1

To determine the empirical formula and molecular formula of n-Butyl phthalate, we need to calculate the molar amounts of carbon and hydrogen in the sample. The empirical formula is C₄H₆O₄ and the molecular formula is C₈H₁2O₈.

Step-by-step explanation:

To determine the empirical formula and molecular formula of n-Butyl phthalate, we need to calculate the molar amounts of carbon and hydrogen in the sample. From the given masses of water and carbon dioxide produced in the combustion analysis and their molar masses, we can calculate the moles of carbon and hydrogen. The empirical formula is the simplest whole number ratio of atoms, so we divide the subscripts by their greatest common factor to obtain the empirical formula. Finally, we calculate the molar mass of the empirical formula and divide the given molecular weight by the empirical formula mass to determine the molecular formula.

The correct empirical formula for n-Butyl phthalate is C₄H₆O₄, and the correct molecular formula is C₈H₁2O₈.