Question

Describe hydration. What properties of water enable its molecules to interact with ions in solution?

Short answer

Hydration is a process where water molecules surround and interact with ions or polar molecules due to the polar nature of water. Water, being a polar molecule due to its bent shape, can interact with ions in solution, with the negative part of the water molecule (oxygen) attracting cations and positive part (hydrogen) attracting anions.

Step-by-step solution

Definition of Hydration

Hydration is a process in which a substance, typically an ion or a polar molecule, gets surrounded by water molecules. This happens due to the attractive force between the water molecules and the ions or polar molecules. This is possible because water molecules are polar in nature.

Understanding Polarity of Water

A water molecule (H2O) is polar because of the bent shape of the molecule where oxygen atom is at the vertex. This shape leads to uneven distribution of charge, with a partial negative (\(\delta-\)) charge around oxygen and partial positive (\(\delta+\)) charges around the hydrogen atoms.

Interaction of Water with Ions in Solution

When an ionic substance is dissolved in water, the negatively charged ions (anions) are attracted to the positively charged (\(\delta+\)) hydrogen part of the water molecule and the positively charged ions (cations) are attracted to the negatively charged (\(\delta-\)) oxygen part of the water molecule, leading to ion-dipole interactions. This process is known as hydration.