Alkanes And Halogenoalkanes Flashcards
(11 cards)
What are alkanes?
Saturated hydrocarbons. Each carbon forms 4 single bonds in an alkane
What is fractional distilation
A method used to separate out crude oil into useful fractions
How does fractional distillation work?
. Crude oil is vapourised at 350°c
. The vapourised crude oil goes into the bottom of the fractionating column and rises up through the trays
. The largest hydrocarbons don’t vapourise because they have too high boiling points, so they collect at the bottom of the column
. Aa crude oil vapourised travels up the column, it gets cooler, creating a temp gradient
. Hydrocarbons with lowest boiling points don’t condense st the top and are drawn off at the top of the column as gas
What is cracking?
Braking long chain alkanes into smaller hydrocarbons (which can include alkenes). This incocpes breaking the c-c bond
What are the 2 types of cracking?
Thermal and catalytic
What is thermal cracking
Take place at high temp, at high pressure. Produces alot of alkenes. These alkenes are used to make heaps of valuable product like polymers. Eg: ploy(ethene)
What is catalytic cracking
It uses a zeolite catalyst at a light pressure at a high temp. It produces aromatic hydrocarbons and alkanes needed to produce motor fuels.
Using catalyst is cheaper coz it’s done at lower pressure and temp and catalyst speeds up rate of reaction so it is also faster
What is complete combustion
When a hydrocarbon is burned completely with oxygen and produces CO² and H²O
What is incomplete combustion
When there is a lack of oxygen when burning a hydrocarbon. This produces carbon (soot), and carbon monoxide gas and/or carbon dioxide
What are the issues with incomplete combustion
It produces carbon monoxide, which is poisonous as it binds to the same sight in heamaglobin as oxygen, so it prevents oxygen from being transported around the body.
Soot can also cause breathing problems and build up in engines so they don’t work properly
