Naphthalene liquifies at precisely 80.26°C. This temperature marks the point at which naphthalene transitions from a solid state to a liquid state, a process commonly known as melting.
Understanding Naphthalene's Melting Point
The temperature at which a substance changes its state from solid to liquid is defined as its melting point. For naphthalene, this critical temperature is 80.26°C. Below this temperature, naphthalene exists as a solid; above it, it will be in its liquid form, assuming atmospheric pressure. This specific physical property is crucial for its identification and various applications.
Here's a quick overview of naphthalene's state change:
| Property | Value |
|---|---|
| Melting Point | 80.26°C |
| State Below Melting Point | Solid |
| State Above Melting Point | Liquid |
| Process of Liquefaction | Melting |
What is Naphthalene?
Naphthalene is a crystalline, aromatic hydrocarbon with the chemical formula C₁₀H₈. It is perhaps best known as the primary ingredient in traditional mothballs due to its distinct, pungent odor and its ability to sublimate (turn directly from solid to gas) at room temperature.
- Appearance: White, volatile solid in its pure form.
- Odor: Strong, distinctive, coal-tar like.
- Source: Naturally found in coal tar and crude oil.
- Key Property: Readily sublimes, meaning it can transition directly from a solid to a gas without first becoming a liquid, especially at ambient temperatures. This sublimation is why mothballs shrink over time.
For more detailed chemical information, you can refer to its profile on PubChem.
The Process of Liquefaction (Melting)
When naphthalene is heated to its melting point of 80.26°C, the kinetic energy of its molecules becomes sufficient to overcome the intermolecular forces holding them in a rigid crystal lattice. At this temperature, the structured solid begins to break down, and the molecules gain enough freedom to move past each other, resulting in the formation of a liquid. This phase transition is reversible; cooling liquid naphthalene below 80.26°C will cause it to solidify again.
Practical Applications and Considerations
Understanding naphthalene's melting point is vital for various industrial and scientific purposes:
- Industrial Synthesis: Naphthalene serves as a precursor in the production of various chemicals, including phthalic anhydride (used to make plastics, dyes, and resins) and certain insecticides. Its precise melting point is a critical parameter in manufacturing processes to ensure purity and control reactions.
- Chemical Purity Testing: The melting point is a sensitive indicator of a substance's purity. Pure naphthalene has a sharp melting point at 80.26°C. Impurities typically broaden the melting range and lower the observed melting point.
- Heat Transfer Applications: While not its primary use, the phase change properties of substances like naphthalene can be considered in specific thermal management designs or experiments where a predictable temperature plateau during phase transition is desired.
- Safety and Handling: Knowing its melting point helps in safe storage and handling. Naphthalene is combustible, and understanding its phase changes is part of assessing its physical and chemical hazards.
Its ability to liquify at a relatively low temperature compared to many other organic compounds makes it useful in laboratory settings for demonstrations involving phase transitions.
