Explain why solutions of HBr in benzene (a nonpolar solvent) are nonconductive, while solutions in water (a polar solvent) are conductive.

The solvation process is crucial in understanding why substances dissolve differently in various solvents. Imagine solvation as a welcoming party, where the solvent molecules surround and interact with the solute particles. Now, polar solvents, like party hosts with a charismatic personality, allure guests with their polar, charged regions. These solvents, such as water, can form strong electrostatic connections with ions or polar molecules. Thus, in a polar solvent, substances like hydrobromic acid (HBr) split up into ions—H+ and Br- in our case—due to these attractive forces.

On the flip side, nonpolar solvents like benzene are like indifferent hosts. They don't possess significant charge differences across their molecules and therefore have little capacity to attract or 'solvate' ions. This means HBr molecules remain in their neutral state, mingling among the benzene molecules without dissociating into their charged counterparts, which in turn keeps the solution nonconductive.

Dissociation is the breakup of a compound into its constituent ions, which is like deciding that a dance partner simply isn't a good match. This process is commonplace for ionic compounds when they're introduced to a polar solvent. Just as pairs on a dance floor might split up to find better matches, ionic compounds like HBr separate into ions when dissolved in water—a suave and charming dance partner known for its polarity.

The positive part of the water molecule (due to hydrogen) dances away with the negatively charged bromide ion (Br-), while the negative part (due to oxygen) grabs the hand of the positively charged hydrogen ion (H+). As a result, these ions are now free to conduct an electric current, moving through the solution to the beat of an electric field. It's a dance of charge that makes solutions in water conductive, unlike in nonpolar solvents where the compounds refuse to split and instead prefer to stick together.

The dielectric constant is the wingman of the electrical world. It's a measure that reflects a substance’s willingness to support electric fields by reducing the force between charges. Higher dielectric constants in solvents like water mean they're better at keeping the ions apart once they've dissociated. Think of it like a matchmaking friend who ensures two attracted people have enough space to interact without immediately sticking together again.

This makes water an excellent solvent for encouraging ionic compounds to dissociate and remain dissociated—providing a space where ions can move independently. This independence parade of ions is what carries an electric current through the solution. In contrast, a solvent with a low dielectric constant, such as benzene, is less effective at this, which contributes to its nature of not sustaining conductivity.