Use your mouse to click-n-drag a square around the image which correctly depicts the hydration of the chloride ion: H2O HCl Cl- {Cl} {Cl} H2O
The Correct Answer and Explanation is:
The correct image that depicts the hydration of the chloride ion (Cl⁻) is the first structure on the left, which is highlighted in green.
Explanation
Hydration refers to the process in which water molecules surround and interact with ions in an aqueous solution. When chloride ions (Cl⁻) dissolve in water, they are stabilized by hydrogen bonding with water molecules.
Water is a polar molecule — the oxygen atom carries a partial negative charge (δ⁻) and the hydrogen atoms carry partial positive charges (δ⁺). Because Cl⁻ is a negatively charged ion, it attracts the partial positive hydrogen ends of water molecules. This attraction leads to the formation of ion-dipole interactions, a type of intermolecular force that occurs between an ion and a polar molecule.
In the correct depiction (the first image), the chloride ion (Cl⁻) is shown surrounded by water molecules, with the hydrogen atoms of water pointing toward the Cl⁻ ion. This is correct because the hydrogen ends (δ⁺) are electrostatically attracted to the negatively charged chloride ion.
The other structures are incorrect for the following reasons:
- Some show the oxygen atom of water facing the Cl⁻ ion, which is incorrect since both oxygen and chloride are negatively charged and would repel each other.
- Some structures show improper orientation or no interaction at all between the water and the Cl⁻ ion, failing to depict hydration.
Proper hydration is essential in biological systems and chemistry because it:
- Helps dissolve salts in water.
- Stabilizes ions in solution.
- Plays a role in conductivity and biochemical reactions.
In conclusion, the first image correctly illustrates hydration of the chloride ion by showing hydrogen atoms of water molecules directed toward the negatively charged chloride, forming stabilizing ion-dipole interactions.
