Mass of CO₂ = 8.59 g
Molar mass of CO₂ = 44 g/mol
Moles of CO₂ = Mass of CO₂ / Molar mass of CO₂ = 8.59 g / 44 g/mol
= 0.1952 moles
Now there is 1 mole of C in 1 mole of CO₂
Therefore, moles of carbon = moles of CO₂ = 0.1952 moles
Mass of carbon = moles of C x the atomic weight of C
= 0.1952 moles x 12 g/mol
= 2.3427 g
Mass of H₂O = 3.52g
Molar mass of H₂O = 18g/mol
Moles of H₂O = 3.52g /18g/mol = 0.1956 moles
Now there is 2 moles of H in 1 mole of H₂O
Moles of H = 0.1956 moles X 2 = 0.3912 moles
Mass of H = 0.3912 moles X atomic mass of H
= 0.3912 moles X 1 g/mol = 0.3912 g
Mass of butyric acid = 4.30g
Mass of O = mass of butyric acid - (mass of C + mass of H)
= 4.30 g - 2.3427 g - 0.3912 g = 1.5661 g
Moles of O = mass of O / atomic mass of O = 1.5661 g / 16 g/mol
= 0.0978 moles
Divide by smallest mole to get the molar ratio
C = 0.1952 moles/0.0978 moles = 2
H = 0.3912 moles/0.0978 moles = 4
O = 0.0978 moles / 0.0978 moles = 1
Empirical formula of butric acid is C₂H₄O
Molecular formula of butric acid is C₄H₈O₂
