Water’s Solvent Properties


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When sodium chloride dissolves in water, the positively charged sodium ions interact with the oxygen of water, and the negatively charged chlorine ions interact with the hydrogen of water.
When we mix table salt (NaCl) in water, it forms spheres of hydration around the ions. Source: OpenStax Biology 2e

OpenStax Biology 2e

Since water is a polar molecule with slightly positive and slightly negative charges, ions and polar molecules can readily dissolve in it. Therefore, we refer to water as a solvent, a substance capable of dissolving other polar molecules and ionic compounds. The charges associated with these molecules will form hydrogen bonds with water, surrounding the particle with water molecules. We refer to this as a sphere of hydration, or a hydration shell, as the image above illustrates and serves to keep the particles separated or dispersed in the water.

– What is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end?

When we add ionic compounds to water, the individual ions react with the water molecules’ polar regions and their ionic bonds are disrupted in the process of dissociation. Dissociation occurs when atoms or groups of atoms break off from molecules and form ions. Consider table salt (NaCl, or sodium chloride): when we add NaCl crystals to water, the NaCl molecules dissociate into Na+ and Cl ions, and spheres of hydration form around the ions. The partially negative charge of the water molecule’s oxygen surrounds the positively charged sodium ion. The hydrogen’s partially positive charge on the water molecule surrounds the negatively charged chloride ion.

– What is a general process in which molecules separate or split into smaller particles such as atoms, ions, or radicals, usually in a reversible manner?


Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e