Chapter 12 Alkanes Flashcards
what is an alkane
saturated hydrocarbon that can be aliphatic or alicyclic
what is the general formula for aliphatic alkanes
CnH2n+2
give 3 reasons why alkanes are very unreactive
>stable >strong bonds >non polar >symmetrical bonds >similar electronegative values
why are alkanes good fuels
because when completely combusted their carbon and hydrogen bonds release lots of energy that can be used
what is a sigma bond
resultant bond when there is a direct overlap of 2 atomic orbitals one from each bonding atom
what is the effect of chain length on boiling point
the longer the chain the higher the boiling point because there is a greater number of induced dipole dipole intermolecular bonds
how are alkanes separated
fractional distillation
how does fractional distillation work
crude oil is pumped into a chamber with different collection points
the chamber is heated causing the lower boiling point alkanes to evaporate and rise whilst high boiling point ones remain in a liquid state
as these different hydrocarbons rise they cool down and collect at different fractions
what is the effect of branching on the boiling point
branching decreases the boiling point because it increases the distance between molecules which weakens the intermolecular forces
what two products can form when an alkane undergoes incomplete combustion
carbon monoxide
soot (carbon) particles
why is incomplete combustion bad
carbon monoxide is poisonous
soot can cause respiratory problems
what do alkanes require to react with halogens
photochemical light such as UV sunlight
what is the product when an alkane and halogen react
haloalkane
what type of reaction is the production of a haloalkane
substitution
