Water is considered to be the ‘universal’ solvent, however, only hydrophilic materials will dissolve in water readily. This lesson discusses the properties of hydrophilic compounds.
Have you ever added sugar to a drink to make it sweeter? What about dissolving salt in water for cooking? Whenever we dissolve compounds or molecules into water, we are taking advantage of the fact that these chemicals are hydrophilic.
If a compound is hydrophilic (or ‘water loving’), then this means the compound readily dissolves in water or a watery solvent. Let’s discuss what makes a molecule hydrophilic.
What Makes a Molecule Hydrophilic?
Water is a polar molecule.
Polar molecules are molecules that have partial charges due to uneven bonding. The oxygen atom in a water molecule is highly electronegative, which means that it will pull the electrons in a bond closer to it. This, in turn, makes oxygen partially negative, and hydrogen partially positive.
Sugar molecules are important for almost all living things, since they represent stored energy that can be used to produce adenosine triphosphate (ATP), a coenzyme that carries energy throughout cells. Sugar molecules are able to dissolve in water, and this allows for most organisms to transport them throughout their bodies in fluid, such as plasma.
Sugars have many hydroxyl groups or -OH groups that are able to interact with water molecules due to the presence of oxygen. These -OH groups give sugar molecules hydrophilic capabilities.
Hydrophilic molecules are molecules that can dissolve in water. These molecules must have a charge (positive or negative) in order to interact with water, which is polar. Meaning that the molecule has a partially positive side and a partially negative side.
In biological systems, it is important that certain materials, such as ions and sugars, maintain hydrophilicity in order to allow for them to circulate and be transported throughout the organism.