[4] Combustion of Alkanes

Why are alkanes good fuels?

• Alkanes are good fuels because during combustion, energy is absorbed to break the C–C and C–H bonds in the alkane and the O=O bonds in oxygen. However, more energy is released when strong C=O and O–H bonds form in the carbon dioxide and water products. This results in a large overall release of heat energy, making alkanes good fuels.

whats wrong with carbon monoxide?

Carbon monoxide is toxic and strongly binds to haemoglobin to form carboxyhaemoglobin, reducing the amount of haemoglobin available to transport oxygen in the blood. This reduces the oxygen supply to respiring tissues.

what is the General reaction for free radical substitution reaction 

alkane + halogen -> haloalkane + hydrogen halide 

What are the limitations of free radical substitution? 

the presence of reactive free radicals makes radical substitution very unpredictable and difficult to control. A chain reaction due to multiple propagation steps causes a mixture of products to be formed. Therefore fractional distillation or chromatography is needed to purity the desired product. 

defitinion of free radical

 
A species with an unpaired electron

what type of fission is free radical substitution

homolytic fission

defitition of a chain reaction

A reaction that is catalysed by a reactive substance

Why can chlorination of propane produce different haloalkanes?

Hydrogen atoms can be substituted at different positions, producing different structural isomers.

Why are tertiary radicals more stable than primary radicals?

Alkyl groups stabilise the radical through electron donation

what makes alkanes stable

• Alkanes have strong, non-polar (sigma) C-C and C-H bonds