What is the Difference Between Naphthalene and p-Dichlorobenzene?

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Naphthalene and p-Dichlorobenzene are two different chemical compounds used as moth repellents and in other applications. Here are the key differences between them:

  • Chemical Structure: Naphthalene has two ring structures fused with each other, while p-Dichlorobenzene has a benzene ring with two chlorine atoms attached.
  • Specific Gravity: The specific gravity of paradichlorobenzene mothballs ranges between 1.429 and 1.437, while the specific gravity of naphthalene mothballs ranges between 1.094 and 1.100. This difference in specific gravity can be used to differentiate between the two types of mothballs.
  • Melting Point: A method has been developed for the rapid, simple differentiation of naphthalene from paradichlorobenzene mothballs based on the difference in their melting points.

Both naphthalene and p-Dichlorobenzene are classified as hazardous air pollutants and can be chronic chemical hazards. They are used in the form of mothballs to repel or kill clothes moths and other insects. Mothballs release a toxic gas that is harmful to insects, but they can also be harmful to people and pets if used in an unconfined space.

Comparative Table: Naphthalene vs p-Dichlorobenzene

Here is a table comparing the differences between naphthalene and p-dichlorobenzene:

Property Naphthalene p-Dichlorobenzene
Molecular Structure Two fused ring structures Single ring structure with two chlorine atoms attached
Formula C10H8 C6H4Cl2
Appearance White, crystalline solid White-colored liquid
Odor Unpleasant, mothball-like Odor of mothballs
Density 0.65 g/mL at 20°C Denser than water
Solubility in Water Insoluble Insoluble
Flash Point Below 200°F (93°C) Below 200°F (93°C)
Common Uses Mothballs, dry cleaning, and as a raw material for the production of dyes Mothballs, disinfectants, and deodorants

Naphthalene and p-dichlorobenzene are both classified as hazardous air pollutants and rank highly among chronic chemical hazards in the U.S.. They have similar uses, such as in mothballs, but differ in their molecular structure, appearance, and other properties.