Why do alkanes have a higher heat of combustion than alkenes?

Alkenes (CnH2n), having a double bond (C=C) in their makeup contain less Hydrogen and therefore will need a little extra oxygen in order to give complete combustion of carbon. That’s why alkanes generally burn with a clean flame.

Why is an alkene more reactive than alkane?

The number of hydrogen atoms in an alkene is double the number of carbon atoms, so they have the general formula. Alkenes are unsaturated, meaning they contain a double bond . This bond is why the alkenes are more reactive than the alkanes .

Are alkenes less flammable than alkanes?

Alkenes combust, but they are less likely than alkanes to combust completely. Incomplete combustion of alkenes occurs where oxygen is limited and produces water, carbon monoxide and carbon (soot). This causes a smoky flame.

Why do alkenes produce a Sootier flame than alkanes?

Why do alkenes burn with a sootier flame than alkanes? – Quora. Well, alkenes clearly have stronger C-C bonds in the olefin. And both alkenes, and long-chain alkanes TEND to combust incompletely. And thus there is more opportunity for the genesis of particulate carbon, as soot, and carbon monoxide.

Do alkenes burn faster than alkanes?

Answer: Alkenes are more reactive than alkanes, as a result of the presence of a carbon double bond. However, if the oxygen is not supplied fast enough, the alkene will burn with a limited oxygen supply and incomplete combustion will result.

Are alkenes more stable than alkanes?

Generally speaking, alkenes are less stable than alkanes. In alkanes, there are only σ bonds (i. e. C-C single bonds and C-H bonds). The bond energy of an average C-C single bond is around 347 kJ/mol, and C-H bond around 308~435 kJ/mol, both of which need a relatively high energy to break.

Why do alkenes burn?

Alkenes tend to burn with sooty, luminous (yellow) flames. This is because the presence of the double bond reduces the amount of hydrogen in the molecule. This means that it will contain a greater proportion of carbon compared to a saturated molecule.

Why are alkenes not burned as fuels?

However, they are NOT used as fuels for two reasons. They are far too valuable for use to make plastics, anti–freeze and numerous other useful compounds. They burn with a more smoky flame than alkanes due to less efficient, and more polluting incomplete combustion, so the heat energy release is lower than for alkanes.

Why are alkenes not usually burned as fuels?

Alkenes are not used as fuels because: They are scarce in nature. They are made from other hydrocarbons to make plastics, anti–freeze and many other useful compounds. They burn with a smoky flame due to less efficient, and more polluting incomplete combustion, so the heat energy release is lower than for alkanes.