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Hydrogen Sulfide Low Boiling Point Reasons
The reason why the boiling point of hydrogen sulfide is relatively low is as follows.
The first one is related to the intermolecular force. Hydrogen sulfide is composed of molecules, and the intermolecular force is van der Waals force. The van der Waals force is weaker than the force of chemical bonds such as ionic bonds and covalent bonds. The force of ionic bonds in ionic compounds is strong, resulting in a high melting boiling point; some covalent compounds also have high melting boiling points due to the network structure of interatomic covalent bonds. However, there is only van der Waals force between hydrogen sulfide molecules, which is weak, so it is easier for molecules to break free from each other and change from liquid to gas state, resulting in a low boiling point.
Furthermore, the influence of hydrogen bonds. Hydrogen bonds are a special intermolecular force, which is stronger than the general van der Waals force. In water, hydrogen fluoride and other substances, hydrogen atoms can form hydrogen bonds because they are connected to atoms with large electronegativity and small radius (such as oxygen and fluorine), causing their boiling point to rise. However, in hydrogen sulfide, the electronegativity of sulfur is smaller than that of oxygen and fluorine. Although hydrogen is connected to sulfur, it is difficult to form effective hydrogen bonds. Without this strong intermolecular force, the boiling point of hydrogen sulfide is not increased by hydrogen bonds and is relatively low.
To sum up, because hydrogen sulfide has only a weak van der Waals force between molecules, and there is no hydrogen bond to enhance the intermolecular force, its boiling point is low.
The first one is related to the intermolecular force. Hydrogen sulfide is composed of molecules, and the intermolecular force is van der Waals force. The van der Waals force is weaker than the force of chemical bonds such as ionic bonds and covalent bonds. The force of ionic bonds in ionic compounds is strong, resulting in a high melting boiling point; some covalent compounds also have high melting boiling points due to the network structure of interatomic covalent bonds. However, there is only van der Waals force between hydrogen sulfide molecules, which is weak, so it is easier for molecules to break free from each other and change from liquid to gas state, resulting in a low boiling point.
Furthermore, the influence of hydrogen bonds. Hydrogen bonds are a special intermolecular force, which is stronger than the general van der Waals force. In water, hydrogen fluoride and other substances, hydrogen atoms can form hydrogen bonds because they are connected to atoms with large electronegativity and small radius (such as oxygen and fluorine), causing their boiling point to rise. However, in hydrogen sulfide, the electronegativity of sulfur is smaller than that of oxygen and fluorine. Although hydrogen is connected to sulfur, it is difficult to form effective hydrogen bonds. Without this strong intermolecular force, the boiling point of hydrogen sulfide is not increased by hydrogen bonds and is relatively low.
To sum up, because hydrogen sulfide has only a weak van der Waals force between molecules, and there is no hydrogen bond to enhance the intermolecular force, its boiling point is low.
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