* Molecular size: Heptane (C7H16) has a longer carbon chain and is therefore larger than pentane (C5H12).
* Surface area: The larger size of heptane means it has a greater surface area.
* Van der Waals forces: Larger molecules with greater surface area have stronger London dispersion forces (a type of van der Waals force). These forces arise from temporary fluctuations in electron distribution within the molecule, creating temporary dipoles that attract neighboring molecules.
* Increased energy required to overcome attraction: Stronger intermolecular forces require more energy to overcome, resulting in a higher boiling point.
In summary: The larger size and greater surface area of heptane lead to stronger London dispersion forces, which require more energy to break, resulting in a higher boiling point compared to pentane.
