*It is an unsaturated compound Because they have more carbon. It burns with a sooty or smoky flame.

*Unsaturated because the double bond makes the combustion of the hydrocarbon harder, and other byproducts may form aside from CO2 and H2O.

The Sooty Flame

When an organic compound burns with a sooty flame, it is an indication that the compound is an unsaturated compound. This can be explained by considering the characteristics of saturated and unsaturated compounds and the products formed during combustion.

Saturated vs. Unsaturated Compounds

1. Saturated compounds: Saturated compounds are those in which all the carbon atoms are bonded to the maximum number of hydrogen atoms, resulting in single bonds only. They have the general formula CnH2n+2, where 'n' represents the number of carbon atoms.

2. Unsaturated compounds: Unsaturated compounds contain one or more multiple bonds between carbon atoms, either double or triple bonds. These multiple bonds can be either carbon-carbon (C=C) double bonds or carbon-carbon (C≡C) triple bonds.

Reason for the Sooty Flame

The sooty flame produced during the combustion of an organic compound indicates the presence of incomplete combustion. Incomplete combustion occurs when there is insufficient oxygen available for complete oxidation of the compound. Instead of the expected products of carbon dioxide (CO2) and water (H2O), incomplete combustion results in the formation of carbon (soot) and carbon monoxide (CO).

Explanation

1. During combustion, organic compounds undergo oxidation, which involves the breaking of carbon-carbon bonds and the formation of new bonds with oxygen.

2. In saturated compounds, the presence of only single bonds between carbon atoms makes them less reactive and more stable. Therefore, complete combustion is favored, resulting in the formation of carbon dioxide and water vapor.

3. However, in unsaturated compounds, the presence of double or triple bonds makes them more reactive than saturated compounds. These multiple bonds provide sites for incomplete combustion to occur.

4. When an unsaturated compound burns, the double or triple bonds break, and the carbon atoms form new bonds with oxygen. However, due to insufficient oxygen supply, the reaction may not proceed to completion.

5. As a result, carbon particles (soot) and carbon monoxide are formed instead of carbon dioxide. The soot particles are black in color and can be seen as a sooty flame.

Conclusion

In summary, when an organic compound burns with a sooty flame, it indicates that the compound is an unsaturated compound. The presence of double or triple bonds in unsaturated compounds allows for incomplete combustion, leading to the formation of carbon particles (soot) and carbon monoxide. The sooty flame is a visual indicator of incomplete oxidation and the presence of unsaturated bonds in the organic compound.