Why is water considered a universal solvent?

It dissolves many, many common things.

Water is considered a universal solvent due to its unique chemical properties. It has the ability to dissolve a wide variety of substances, including many common substances like salts, sugars, and polar compounds. This ability is primarily due to the polar nature of water molecules.

To understand why water is a universal solvent, let's first look at its molecular structure. A water molecule is made up of two hydrogen atoms covalently bonded to one oxygen atom. The oxygen atom is more electronegative, which means it has a stronger attraction for electrons. As a result, the oxygen atom pulls the shared electrons towards itself, creating a slightly negative charge (δ-) on the oxygen atom and a slightly positive charge (δ+) on the hydrogen atoms.

This uneven distribution of charge within the water molecule makes it a polar molecule. The positive end of one water molecule is attracted to the negative end of another water molecule, creating intermolecular forces known as hydrogen bonds. These hydrogen bonds are relatively weak individually but collectively can have significant effects on the solvation of substances.

When water comes into contact with a solute, such as a salt or sugar, the polar water molecules surround the solute particles, separating the individual ions or molecules from each other. The positive ions are attracted to the negative ends of the water molecules (oxygen), while the negative ions are attracted to the positive ends of the water molecules (hydrogen). This process of solvation or dissolving allows water to break apart and disperse many substances.

Another reason why water is a universal solvent is its ability to dissolve polar compounds. Polar compounds have charged or partially charged regions, making them capable of forming interactions with water molecules. Water's polarity allows it to form hydrogen bonds with polar compounds, effectively dissolving them.

Overall, the polar nature of water molecules, the formation of hydrogen bonds, and its ability to interact with various types of solutes make water an excellent universal solvent.