What is Hydrophobicity?
To be hydrophobic means to fear water. Hydrophobic molecules and surfaces repel water while hydrophobic liquids separate from water. Water is polar, meaning it has an uneven distribution of electron density among its atoms. Hydrophobic molecules are nonpolar (have no positive or negative charge). They do not produce a static electric field. When molecules are polar, opposite regions of electrical energy attract water molecules. Because there are no opposite electrical charges on hydrophobic molecules, water cannot form hydrogen bonds with the molecules. The water molecules form hydrogen bonds with themselves, and the nonpolar molecules clump together.
What are some Hydrophobic Substances?
Oil is one of the most common hydrophobic substances. When it is put in water it separates. Greases, waxes, fats, and steroids are also hydrophobic. These substances do not dissolve in water; they repel it. For example, car wax is used to repel rainwater and causes it to bead on a car's surface.
Science Experiments You Can Do at Home
Before performing any experiments, make sure you have an adult present. To see hydrophobicity in action, take a spoon of cocoa powder and dip it in a cup of water. You will see that the cocoa powder comes out exactly the same. Dip it in the water again and you will see that it is slightly wet. Tap the cocoa with another utensil and will dry again! This is because the cocoa powder contains fat which as we mentioned above is hydrophobic. This allows the layer of water to disappear when you tap it with another utensil.
Written by: Maysa Nashawati
Works Cited:
Anne Marie Helmenstine, Ph.D. “The Definition of Hydrophobic With Examples.” ThoughtCo, www.thoughtco.com/definition-of-hydrophobic-605228.
“Hydrophobic: Definition & Examples (Molecules & Substances).” Tutors.com, tutors.com/lesson/hydrophobic-substances-definition-examples#:~:text=Hydrophobic%20materials%20in%20biology%20are%20substances%20that%20do,an%20affinity%20to%20bond%20to%20other%20nonpolar%20substances.
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