Organic - Alkanes Flashcards
what is crude oil?
a mixture of different hydrocarbons
why can crude oil be separated into the separate molecules by fractional distillation?
as the different chains lengths of molecules result in them having different boiling points
by what process can crude oil be separated into the separate molecules?
fractional distillation
how does the temperature change moving up a fractioning column?
it is hottest at the bottom and cooler at the top
where in the column do shorter chain hydrocarbons condense? why?
high up the column because they have lower boiling points
where in the column do longer chain hydrocarbons condense? why?
nearer the bottom because they have lower boiling points
after fractional distillation, what happens to the products to break them down further?
cracking
why are hydrocarbons cracked?
to turn longer carbon chains into more useful smaller molecules
why are harsh reaction conditions required for cracking?
because C-C bonds are broken
what are the 2 main types of cracking?
thermal cracking
catalytic cracking
what are the main products of thermal cracking?
high proportion of alkanes and alkenes
what are the conditions for thermal cracking?
high temperature (around 1200 K)
high pressure (around 7000 kPa)
what are the main products of catalytic cracking?
aromatic compounds with carbon rings
what are the conditions required for catalytic cracking?
lower temperatures (than thermal) (around 720 K)
normal pressure
zeolite catalyst
why do alkanes make good fuels?
they release a lot of energy when burned
