Final answer:
For a compound with molecular formula C8H11N, the empirical formula is C5H7N with a mass of 81.13 amu/formula unit. Isomers with the same molecular formula but different structures are possible; additional spectral data is necessary to determine the exact structure.
Step-by-step explanation:
An appropriate structure for a compound with the molecular formula C8H11N involves determining the empirical formula based on molar ratios. The empirical formula gives the simplest whole-number ratio of atoms in a compound. Considering the provided empirical formula, C5H7N, we know that the empirical formula mass is 81.13 amu/formula unit, which is also 81.13 g/mol formula unit.
When discussing possible structures for the given molecular formula, isomerism should be considered, as there can be various structures, known as isomers, with the same molecular formula. For example, with C4H10, the two isomers boil at distinctly different temperatures, one at −0.5°C and the other at −11.7°C. This illustrates the concept of isomers, which can greatly differ in their physical and chemical properties even though they share the same molecular formula.
The structure of the compound C8H11N could potentially be an alkylated aromatic compound such as an ethylbenzene derivative, or a more complex structure featuring a nitrogen heteroatom in an amine, amide, or other nitrogen-containing functional group. To pinpoint the exact structure, additional information like NMR or IR spectra would usually be needed.