In chemistry, 'apolar' (also spelled 'nonpolar') describes a molecule or chemical group where the electrons are shared equally between atoms, resulting in no significant separation of electrical charge. This even distribution creates an absence of distinct positive and negative poles. apolar substances typically exhibit weak intermolecular forces, such as London dispersion forces, leading to lower melting and boiling points compared to polar substances. They often dissolve well in other apolar solvents but poorly in polar solvents like water.
Apolar meaning with examples
- Hexane is an apolar solvent commonly used in labs. It effectively dissolves nonpolar substances, like fats and oils, which can be extracted from mixtures using hexane. The apolar nature of the hexane allows for easy separation of nonpolar substances. Its interactions with other molecules are primarily London dispersion forces, leading to its ability to separate a substance from a polar medium.
- The structure of methane, with its four identical carbon-hydrogen bonds, makes it an apolar molecule. This lack of polarity is the reason methane is a gas at room temperature and has a low boiling point. Methane's apolar character also prevents it from dissolving in water, as water molecules form strong hydrogen bonds which are incompatible with the apolar nature of methane.
- Fats and oils are largely composed of long hydrocarbon chains. These chains are apolar due to the even distribution of electrons. This is why fats and oils don't mix with water and can often be extracted or separated from an aqueous solution using an apolar solvent to dissolve the fats. Their apolar character governs their interactions with other apolar molecules, leading to their distinctive physical properties.
- Many polymers used in plastics are apolar. For example, polyethylene is composed of long chains of carbon and hydrogen atoms. This absence of polarity is a critical factor in the polymer's properties, including flexibility and resistance to water. The apolar nature of the bonds allows for them to be used in many environments without degrading under most conditions.