Shanxian Chemical
SUPPLEMENTS
Ethanol and Water Hydrogen Bonding
The hydrogen bond between ethanol and water is the key to the interaction between substances. In ethanol ($C_2H_5OH $), the hydrogen atom of the hydroxyl group ($-OH $) has a partial positive charge due to the strong electronegativity of the oxygen atom. In water ($H_2O $), there is also a hydrogen-oxygen bond, and the electronegativity of oxygen causes hydrogen to have a partial positive charge.
When ethanol is mixed with water, the hydrogen of the ethanol hydroxyl group and the oxygen of the water molecule, and the hydrogen of the water molecule and the oxygen of the ethyl alcohol hydroxyl group, can form a hydrogen bond. Although the force of this hydrogen bond is weaker than the covalent bond, it is crucial to determine many physical properties of ethanol and water.
If the two have excellent miscibility, they benefit from the hydrogen bond. Hydrogen bonds make ethanol and water molecules attract each other and mix uniformly. And the boiling point of the mixed system is also affected by hydrogen bonds. Compared with pure ethanol or water, the intermolecular force of the mixed liquid is enhanced, and more energy is required to boil it, so the boiling point changes.
Furthermore, in terms of the density of the solution, under the action of hydrogen bonds, the molecules are arranged more tightly or loosely, which has a corresponding effect on the density. This is due to the hydrogen bond between ethanol and water, which changes the properties of the system.
When ethanol is mixed with water, the hydrogen of the ethanol hydroxyl group and the oxygen of the water molecule, and the hydrogen of the water molecule and the oxygen of the ethyl alcohol hydroxyl group, can form a hydrogen bond. Although the force of this hydrogen bond is weaker than the covalent bond, it is crucial to determine many physical properties of ethanol and water.
If the two have excellent miscibility, they benefit from the hydrogen bond. Hydrogen bonds make ethanol and water molecules attract each other and mix uniformly. And the boiling point of the mixed system is also affected by hydrogen bonds. Compared with pure ethanol or water, the intermolecular force of the mixed liquid is enhanced, and more energy is required to boil it, so the boiling point changes.
Furthermore, in terms of the density of the solution, under the action of hydrogen bonds, the molecules are arranged more tightly or loosely, which has a corresponding effect on the density. This is due to the hydrogen bond between ethanol and water, which changes the properties of the system.
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