Reasons that alkanes are better fuels than alkenes?

Question

I'm only in high school, so please keep the answers fairly simple! I can't find this info anywhere on the internet.... Thanks a lot.

Answer 1

The ratio of Hydrogen to Carbon is more.

Reasons for considering better fuel:
1.Calorific Value
2.Availability

Calorific value is the heat given off when a specific amount(1 mol) of it is burned and measured in kJ/mol

Since both hydrogen and carbon are oxidized to water and Carbon dioxide respectively, and since (as I said earlier) in 1 mol of alkane there are 2 hydrogen atoms more than a corresponding alkene of same number of carbon atoms calorific value is more.

Also alkanes are more abundant.

Compare the calorific values of ethane and ethylene from the internet and see for it yourself!

Thus alkanes are better fuels than alkenes!

Answer 2

Fuel is related to the amount of energy released when the chemical bonds are broken. Now, alkanes have a lot of single bonds and alkenes have double bonds. But the amount of energy "stored as fuel" in a double bond is not twice of two single bonds. It is less. Compare the combustion equations of C2H6, an alkane and C2H4, an alkene. Laying out the Lewis structure you will see that the alkane has seven bonds to be broken while the alkene has, say 5 and 2/3 bonds, which is less. Thus less energy released for alkenes.

Answer 3

I refer on your unique question, on why short-chained Alkanes are sturdy fuels. the respond is as follows: - short-chained alkanes has smaller molecules which makes it easier to burn. the explanation why we don't burn bigger fractions is with the aid of the fact it quite is not useful. at the start, the "highway tar", which I call bitumen, takes an prolonged time to burn, and demands a severe volume of temperature( over 4 hundred degree celsius). truthfully that's a threat for autos to have engines working over 4 hundred degree celsius? subsequently, in spite of better fractions having the greater beneficial warmth output, it would not unavoidably propose that greater skill is being produced. I actuality, greater skill is lost via fact it gets switched over into warmth. while smaller fractions are easier to burn, and produces the