When it comes to chemistry, one of the most fundamental concepts that you will learn is the boiling point of a substance. This is the temperature at which a liquid turns into a gas by overcoming the intermolecular forces that hold the molecules together. However, not all liquids have the same boiling point, and this is due to a variety of factors. In this article, we will explore why ethanol has a higher boiling point than ethane.

What is Ethanol?

Ethanol is a clear, colorless, and flammable liquid that is commonly known as alcohol. It has a chemical formula of C2H5OH, which means that it is composed of two carbon atoms, six hydrogen atoms, and one oxygen atom. Ethanol is produced by the fermentation of sugars and starches, which is a process that is commonly used in the production of alcoholic beverages. It is also used as a fuel, solvent, and disinfectant.

What is Ethane?

Ethane is a colorless, odorless, and flammable gas that is commonly used as a fuel. It has a chemical formula of C2H6, which means that it is composed of two carbon atoms and six hydrogen atoms. Ethane is produced during the refining of petroleum and natural gas, and it is also used as a feedstock for the production of other chemicals such as ethylene and polyethylene.

What Determines the Boiling Point of a Substance?

The boiling point of a substance is determined by the strength of the intermolecular forces that hold the molecules together. Intermolecular forces are the attractive forces between molecules, and they can be divided into three main types: London dispersion forces, dipole-dipole forces, and hydrogen bonding.

London dispersion forces are the weakest of the intermolecular forces and are present in all molecules. They arise from temporary fluctuations in the electron distribution within a molecule, which can create temporary dipoles. These temporary dipoles can induce similar temporary dipoles in nearby molecules, creating a weak attraction between them.

Dipole-dipole forces are present in polar molecules and arise from the attraction between the positive end of one molecule and the negative end of another. These forces are stronger than London dispersion forces.

Hydrogen bonding is a special type of dipole-dipole force that occurs when a hydrogen atom is bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. The hydrogen atom becomes partially positive, while the electronegative atom becomes partially negative, creating a strong attraction between the two molecules.

Why Does Ethanol Have a Higher Boiling Point Than Ethane?

Now that we understand the intermolecular forces that determine the boiling point of a substance, we can investigate why ethanol has a higher boiling point than ethane.

Firstly, ethanol is a larger molecule than ethane, which means that it has more electrons and can form stronger London dispersion forces. This is because larger molecules have a larger surface area, which means that they can come into contact with more neighboring molecules.

Secondly, ethanol is a polar molecule because of the presence of the hydroxyl (-OH) group. This means that it can form dipole-dipole forces with other polar molecules, which are stronger than London dispersion forces.

Finally, ethanol can also form hydrogen bonds with other ethanol molecules because of the presence of the hydroxyl group. This is a very strong intermolecular force that requires a significant amount of energy to overcome, which is why ethanol has a higher boiling point than ethane.

Conclusion

In summary, the boiling point of a substance is determined by the strength of the intermolecular forces that hold the molecules together. Ethanol has a higher boiling point than ethane because it is a larger molecule, is polar, and can form hydrogen bonds with other ethanol molecules. Understanding the factors that determine the boiling point of a substance is important in many areas of chemistry, including the production of fuels, solvents, and chemicals.

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