The empirical formula of the compounds is CH₂. Dividing the given molecular masses by the empirical formula mass gives factors of 2 and 4, leading to molecular formulas of C₂H₄ for the first compound and C₄H₈ for the second.
To find the empirical formula of a compound with 85.62% carbon (C) and 14.38% hydrogen (H), we first assume a 100 g sample to simplify calculations. This means we have 85.62 g of C and 14.38 g of H. To convert these into moles we use atomic masses: C (12.01 g/mol) and H (1.008 g/mol).
Moles of C = 85.62 g ÷ 12.01 g/mol = approximately 7.13 mol
Moles of H = 14.38 g ÷ 1.008 g/mol = approximately 14.26 mol
The mole ratio of C to H is roughly 1:2, so the most simplified ratio of the two elements is CH₂, which is the empirical formula.
Next, to find the molecular formulas, we divide the given molecular masses by the empirical formula mass (C: 12.01 amu, H: 1.008 amu). The empirical formula mass of CH₂ is 14.026 amu.
Molecular Mass of Compound 1 = 28.03 amu
Molecular Mass of Compound 2 = 56.06 amu
Divide these by the empirical formula mass:
28.03 amu ÷ 14.026 amu = 2
56.06 amu ÷ 14.026 amu = 4
These are the factors by which we multiply the empirical formula. Thus, the molecular formula for the first compound is C₂H₄ (ethene) and for the second it's C₄H₈ (butene). These compounds are different isomers of each other, sharing the same empirical formula but having distinct molecular structures and properties.