Question

rank the following compounds according to their heat of combustion. compound compound name heat of combustion 2 - methylheptane select 4 (highest) 3 2 1 (lowest) 2 - methylhexane select nonane select octane select

Explanation:

Step1: Understand heat - of - combustion principle

The heat of combustion of hydrocarbons generally increases with the number of carbon atoms. For isomers, the more branched - out isomer has a lower heat of combustion due to greater stability.

Step2: Count carbon atoms

2 - methylheptane has 8 carbon atoms, 2 - methylhexane has 7 carbon atoms, nonane has 9 carbon atoms, and octane has 8 carbon atoms.

Step3: Compare non - isomers first

Nonane has the most carbon atoms among them, so it has the highest heat of combustion (rank 4). 2 - methylhexane has the fewest carbon atoms, so it has the lowest heat of combustion (rank 1).

Step4: Compare isomers

Between 2 - methylheptane and octane (both with 8 carbon atoms), 2 - methylheptane is branched, so it is more stable and has a lower heat of combustion than octane. Octane ranks 3 and 2 - methylheptane ranks 2.

Answer:

2 - methylheptane: 2
2 - methylhexane: 1
Nonane: 4
Octane: 3