The physical properties and thermodynamic stability of alkanes are governed by molecular weight, chain topology (linear versus branched), and intermolecular forces known as London dispersion forces. As the carbon chain lengthens or branches decrease to increase linearity, these non-covalent interactions strengthen, resulting in increased melting points, boiling points, densities, and heats of combustion relative to isomers. Conversely, branching reduces surface area for contact between molecules, weakening intermolecular attractions to lower phase transition temperatures while enhancing thermodynamic stability through reduced absolute heat of combustion values; however, the inherent non-polarity of C–H bonds ensures that these substances remain insoluble in polar solvents like water regardless of structural variations.
The physical properties and thermodynamic stability of alkanes are governed by molecular weight, chain topology (linear versus branched), and intermolecular forces known as London dispersion forces. …