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Stearic Acid Melting Point 69C Reason
The reason why the melting point of stearic acid is 69 ° C
The melting point of stearic acid is set at 69 ° C, there must be a reason. Cover stearic acid is a long-chain saturated fatty acid with a molecular structure of CH
One is due to the intermolecular force. The stearic acid molecule contains a long hydrocarbon chain, and there is a van der Waals force between this long chain. The hydrocarbon chain increases, and the van der Waals force increases. If the intermolecular force is strong, more energy is required to overcome it, causing the molecule to break free and change from solid to liquid, so the melting point increases.
Second, the crystal structure is related. When stearic acid is in the solid state, the molecules are arranged in an orderly manner to form a crystal structure. Its molecules are closely arranged and regular, and the lattice energy is large. To destroy this ordered crystal structure requires high energy, resulting in a melting point of 69 ° C.
Third, the influence of hydrogen bonds. Although stearic acid carboxyl groups can form hydrogen bonds, long carbon-hydrogen chains account for a large proportion. In general, hydrogen bonds have less effect on the melting point than intermolecular van der Waals forces and crystal structures. However, hydrogen bonds still affect the intermolecular binding force to a certain extent and contribute to the melting point.
In summary, intermolecular van der Waals forces, crystal structures and hydrogen bonds are combined, resulting in a melting point of stearic acid of 69 ° C.
The melting point of stearic acid is set at 69 ° C, there must be a reason. Cover stearic acid is a long-chain saturated fatty acid with a molecular structure of CH
One is due to the intermolecular force. The stearic acid molecule contains a long hydrocarbon chain, and there is a van der Waals force between this long chain. The hydrocarbon chain increases, and the van der Waals force increases. If the intermolecular force is strong, more energy is required to overcome it, causing the molecule to break free and change from solid to liquid, so the melting point increases.
Second, the crystal structure is related. When stearic acid is in the solid state, the molecules are arranged in an orderly manner to form a crystal structure. Its molecules are closely arranged and regular, and the lattice energy is large. To destroy this ordered crystal structure requires high energy, resulting in a melting point of 69 ° C.
Third, the influence of hydrogen bonds. Although stearic acid carboxyl groups can form hydrogen bonds, long carbon-hydrogen chains account for a large proportion. In general, hydrogen bonds have less effect on the melting point than intermolecular van der Waals forces and crystal structures. However, hydrogen bonds still affect the intermolecular binding force to a certain extent and contribute to the melting point.
In summary, intermolecular van der Waals forces, crystal structures and hydrogen bonds are combined, resulting in a melting point of stearic acid of 69 ° C.
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