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Burning of naphthalene on a spatula gives a ________.
red flame
clean flame
yellow flame
sooty flame
yellow flame
Burning of naphthalene on a spatula produces a sooty (or smoky) flame due to its high carbon-to-hydrogen ratio. Aromatic hydrocarbons like naphthalene undergo incomplete combustion in air, releasing unburnt carbon particles as soot.
Burning of naphthalene on a spatula produces a sooty (or smoky) flame due to its high carbon-to-hydrogen ratio. Aromatic hydrocarbons like naphthalene undergo incomplete combustion in air, releasing unburnt carbon particles as soot.
Burning a piece of plastic or old car tire outdoors creates a thick black smoke cloud because there isn't enough oxygen to burn all the carbon cleanly, which is exactly what happens with naphthalene.
Aromatic = Always Sooty (Aromatic rings have high carbon content, so they burn with a smoky/sooty flame).
C10тАЛH8тАЛ+12O2тАЛтЖТ10CO2тАЛ+4H2тАЛO тАФ Ideal complete combustion of naphthalene
\text{Carbon-to-Hydrogen Ratio} =$$\frac{\text{Moles of C}}{\text{Moles of H}}
Naphthalene (C10тАЛH8тАЛ) is an aromatic hydrocarbon with a very high percentage of carbon by mass. When heated in air on a spatula, the available oxygen is insufficient for complete oxidation to carbon dioxide and water. The excess carbon atoms form glowing incandescent particles that emit yellow light and escape into the air as black soot (carbon smoke).
Naphthalene is a polycyclic aromatic hydrocarbon (PAH) with the formula C10тАЛH8тАЛ.
Aromatic compounds contain a high percentage of carbon and generally burn with a smoky or sooty flame.
Alkanes (saturated hydrocarbons) typically burn with a clean, blue, non-sooty flame in sufficient oxygen.
Unsaturated hydrocarbons (alkenes, alkynes) and aromatic compounds burn with a yellow, luminous, and sooty flame due to incomplete combustion.
Useful in chemistry practicals to distinguish between aliphatic and aromatic hydrocarbons based on flame characteristics.
Produces toxic soot and unburnt carbon particulates which contribute to air pollution.
Laboratory identification tests for aromaticity of organic compounds.
Manufacture of phthalic anhydride, dyes, and mothballs.
Naphthalene sublimes readily at room temperature and has a strong characteristic mothball odor.
Option A (red flame) is incorrect as flame color is typically yellow-orange due to incandescent carbon particles.
Option B (clean flame) is incorrect because clean flames are characteristic of saturated aliphatic hydrocarbons with lower carbon content.
Option D (yellow flame) is partially descriptive of the luminosity, but 'sooty flame' is the specific and complete scientific term expected in competitive exams for aromatic combustion.
C is correct тАФ Burning of naphthalene on a spatula gives a sooty flame due to the high percentage of carbon leading to incomplete combustion.
Always remember: Aliphatic saturated hydrocarbons burn with a clean blue flame, whereas unsaturated and aromatic hydrocarbons burn with a yellow, sooty flame due to incomplete combustion.
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