Day: November 28, 2016

How intermolecular forces affect the boiling of a substance

How intermolecular forces affect the boiling of a substance

How intermolecular forces affect the boiling of a substance

11/28/16

“How does the molecular bond type of a chemical affect the boiling point of a substance?”

 

In a Chemistry class, you will probably learn that a chemical’s intermolecular force type will have an effect on the boiling point of a substance. However, there is also a good chance that you will never be explained why such a phenomena occurs. And since we were just told a fact without an explanation, we must investigate. Well, first of all, we know that raising the temperature of a substance will increase the kinetic energy of molecules, and if the kinetic energy is raised high enough, then the molecules will be able to escape from their intermolecular constraints. consequently, if the molecules in a liquid are able to escape, then a the free molecules will form a gas, causing the liquid to boil. And since the different types of intermolecular forces have different strengths, then these more powerful bonds will have more force, and as a result the more powerful the type of bond, the higher the boiling point. To give an example, let’s examine two different chemicals with a similar molecular geometry but different types of bond, Water [H2O] and Hydrogen Sulfide [H2S]. Even though H2S has a higher electron count than H2O, since H2O exhibits hydrogen bonding, the boiling point of H2S (-60 C)  is far lower than the boiling point of H20 (100 C)