What trend is observed as the number of carbon atoms in a hydrocarbon increases?

As the number of carbon atoms in a hydrocarbon increases, both the melting point and the boiling point generally increase. This trend occurs because larger hydrocarbons have greater molecular mass and increased surface area, allowing for stronger van der Waals forces (a type of intermolecular force) between their molecules. As these attractive forces become stronger, more energy is required to change the state of the substance from solid to liquid (melting) or from liquid to gas (boiling). Therefore, larger hydrocarbons will typically have higher melting and boiling points compared to smaller hydrocarbons. This property is significant in understanding how hydrocarbons behave under different conditions and in various applications, such as fuels and lubricants.