4.1.2 alkanes Flashcards
what is an alkane
saturated hydrocarbons
what is the general formula of an alkane
C n H 2n+2
what shape of molecule surrounds each carbon and what is the bond angle
tetrahedral
109.5
how does increased chain length effect boiling point
the re are more points of contact so the intermolecular London forces are stronger so it takes more energy to overcome them
how does branching effect boiling point
it decreases points of contact so boiling point decreases as the London forces are weaker to overcome
why are alkanes good fuels
they release a lot of energy per mole when they burn
what is complete combustion
when and alkane is burnt with excess oxygen to form carbon dioxide and water
what is incomplete combustion
when and alkane is burnt with limited oxygen to form carbon monoxide and water
why is carbon monoxide poisonous
it is better at binding to haemoglobin than oxygen so less oxygen can be carried around or bodies leading to oxygen deprivation
what is the initiation step
formation of free radicals
what kind of reaction is it when an alkane reacts to form a haloalkane and what conditions/reagents are needed
free radical substitution
UV light and halogen
what is the propagation step
free radicals are used up and made in a chain reaction
what is the termination step
free radicals bind with each other to make stable molecules
what are the limitations of free radical substitution
a mixture of organic products is formed by further substitution and reactions at different positions in a carbon chain
why are alkanes not very reactive
they only contain sigma bonds
