Question

Upon combustion, a 0.8376 g sample of a compound containing only carbon, hydrogen, and oxygen produces 1.6003 gco2 and 0.9827 gh2o. find the empirical formula of the compound.

Answer 1

Answer is: empirical formula for compound is C₂H₆O.
m(CO₂) = 1,6003 g.
n(CO₂) = m(CO₂) ÷ M(CO₂).
n(CO₂) = 1,6003 g ÷ 44 g/mol.
n(CO₂) = 0,0364 mol.
n(CO₂) = n(C).
m(C) = 0,0364 mol · 12 g/mol = 0,4368 g.
m(H₂O) = 0,9827 g.
n(H₂O) = 0,9827 g ÷ 18 g/mol.
n(H₂O) = 0,0546 mol.
n(H) = 2 · n(H₂O) = 0,1092 mol.
m(H) = 0,1092 mol · 1 g/mol = 0,1092 g.
m(O) = 0,8376 g - 0,4368 g - 0,1092 g = 0,2916 g.
n(O) = 0,2916 g ÷ 16 g/mol = 0,0182 mol.
n(C) : n(H) : n(O) = 0,0364 mol : 0,1092 mol : 0,0182 mol.
n(C) : n(H) : n(O) = 2 : 6 : 1.