Hydrophilic vs Hydrophobic
“Hydro” means water. From the initial stages of earths’ evolution, water has been a major part of the earth. As for today, water covers more than 70% of the earths’ surface. From this, a larger portion of water is in the oceans and seas, which is about 97%. Rivers, lakes, and ponds have 0.6% of water, and about 2% is there in polar ice caps and glaciers. Some amount of water is present in the underground, and a minute amount is in the gas form as vapors and in clouds. Water is something we cannot live without. Since water is a universal solvent, it participates in most reactions. It is the most abundant inorganic compound in living matter. More than 75% of our body composes of water. It is a component of cells, act as a solvent and reactant. Water is the medium for almost all the biological reactions. Therefore, the capacity of compounds to interact with water is crucial. The degree of this capacity is explained by the two terms hydrophilic and hydrophobic.
Hydrophilic means water loving. Water is polar molecule. Hydrophilic substances are water loving substances; therefore, they like to interact with water or they are dissolved in water. As the phrase “like dissolves like” says, to interact or dissolve in polar molecule like water, the hydrophilic substance should also be polar. So if, there is even a part of a big molecule which is a polar, that end can attract water. For example, the phospholipid molecules, which forms the membrane of the cell, has a hydrophilic phosphate group. Though, the whole molecule is not hydrophilic (the large lipid part of the molecule is hydrophobic), that phosphate head is hydrophilic, thus interacts with water. In contrast to molecules like this, some substances are very hydrophilic. For example, salts and sugar attract water so easily. They even have the ability to attract moisture from the air, so when they are exposed to air they tend to dissolve over time. This happens spontaneously because it is thermodynamically favorable. The substances tend to dissolve in water because; they form hydrogen bonds with water. Usually, hydrophilic substances have a charge separation which makes them polar and capable of hydrogen bonding with water. Hydrophilic substances are used to draw water and keep material dry.
Hydrophobic is the opposite side of hydrophilic. As the name suggests, “hydro” means water, and “phobic” means fear. So the substances, which don’t like water, are known as hydrophobic. Therefore, they repel water molecules. Non-polar substances show this kind of behavior. In other words, hydrophobic substances like to interact with or dissolve in non-polar solvents like oil, hexane etc. Thus, hydrophobic substances are also known as lipophilic (fat loving). When hydrophobic substances are in water, they combine together and repel water molecules. Hydrophobic solvents are important to separate water immiscible substances from water.
What is the difference between Hydrophilic and Hydrophobic?
• Hydrophilic means water loving and hydrophobic means fear of water.
• Therefore, hydrophilic substances interact with and dissolve in water, whereas hydrophobic substances do not show such behavior.
• Hydrophilic substances are polar, and hydrophobic substances are non-polar.