London Forces Interaction
In alkanes, melting points increase as molecular size increases, with a larger surface area producing greater attraction due to London forces.
Boiling Points in Alkanes
Boiling points also increase with molecular weight, as heavier molecules require more energy to transition from liquid to gas.
Linear and Branched Alkanes
Branched alkanes have smaller surfaces than their linear isomers, resulting in weaker attractive forces and, consequently, lower melting and boiling points.
2-Methylbutane (a branched alkane) has a lower boiling point than pentane (a linear alkane).
Water Solubility
Alkanes are insoluble in water due to their almost null polarity. Their densities range between 0.6 and 0.8 g/ml, so they float on water.