Quick question - I understand why ethanol is soluble in water, because it can form hydrogen bonds, but why is it also soluble in benzene, a nonpolar solvent?
The ethyl group has enough of the non-polar characteristics (like dissolves in like) to be similar to benzene. See this summary at the top of the link and see other links below the summary.
https://www.google.com/search?q=ethanol+solubility+inh+benzene&ie=utf-8&oe=utf-8&client=firefox-b-1
Great question! Ethanol (C2H5OH) is indeed soluble in both water and benzene, despite the fact that these solvents have different polarities. The solubility of ethanol in benzene can be explained by intermolecular forces.
Ethanol is a polar molecule due to the presence of an oxygen atom with two lone pairs of electrons, which creates a partial negative charge (δ-) and the carbon and hydrogen atoms, which create a partial positive charge (δ+). This polarity allows ethanol to interact with other polar molecules, such as water, through hydrogen bonding.
In water, ethanol can form hydrogen bonds with the water molecules. The oxygen atom of ethanol interacts with the hydrogen atoms of water, and vice versa. This leads to the dissolution of ethanol in water.
On the other hand, benzene is a nonpolar solvent. It consists of a ring of six carbon atoms with alternating double bonds (C6H6). Since benzene has a symmetrical structure, it does not possess a permanent dipole moment. In other words, it lacks a significant positive or negative charge distribution. Hence, there is no possibility for hydrogen bonding between ethanol and benzene.
However, despite the absence of hydrogen bonding, ethanol can still dissolve in benzene through a different type of intermolecular force called London dispersion forces or van der Waals forces. These forces are weak interactions that occur between temporary fluctuations in electron density. Within benzene, the π-electron clouds create regions of temporary positive and negative charge densities. Ethanol's polar nature allows it to interact with these temporary charges, leading to solvation or dissolution of ethanol in benzene.
In summary, ethanol's ability to dissolve in benzene is primarily due to the weak intermolecular forces called London dispersion forces. While hydrogen bonding is the primary force that enables ethanol's solubility in water, ethanol's polarity allows it to interact with temporary charge densities in benzene, leading to solubility in this nonpolar solvent.