crude oil

what is crude oil

a mixture of hydrocarbons

how are the different compounds in crude oil separated

by fractional distillation

describe separating crude oil

1) Crude oil is heated to make vapour

2) Vapour rises up the column

3) The column is hot at the bottom and cooler at the top

4) Hydrocarbons condense at different temperatures depending on their boiling points

what liquid is drained off at the bottom of the fractionating column

bitumen

what type of boiling point do longer hydrocarbons have and where do they condense and drain out of the column

- high bpt

- condense and drain out of the column early on when they are near the bottom

what do bubble caps in the fractionating column do

- stop the separated liquids from running back down the column

- and remixing

what does the fractionating column separate the crude oil into

different fractions

fraction

a set of hydrocarbon molecules of similar size and similar boiling points

what type of hydrocarbons can the fraction contain

both saturated and unsaturated hydrocarbons

order of fractions from top to bottom

- refinery gases

- gasoline

- kerosene

- diesel

- fuel oil

- bitumen

(bfdkgr)

refinery gases use

-bottled gas

- domestic heating and cooking

gasoline use

petrol, fuel for cars

kerosene

aircraft fuel

diesel oil

fuel for lorries, buses

fuel oil

fuel for ships, power stations

bitumen

for road surfacing

volatility of large molecules

large molecules are less volatile (harder to turn into vapour)

vicosity of large molecules

large molecules have higher viscosity (harder/slower to flow)

flammablility of large molecules

large molecules are less flammable

colour of large molecules and colour increases

large molecules are darker (colourless -> yellow -> brown -> black)

why is there a higher demand for short-chain hydrocarbons

- shorter chains are more flammable + easier to ignite

- this makes them very useful as fuels

intermolecular forces of long chain molecules

longer chain molecules have stronger intermolecular forces

what do we do to turn long chains into short chains

catalytic cracking

what is cracking a form of

thermal decomposition

thermal decomposition

breaking molecules down into simpler molecules by heating them

what does cracking also produce and why is this useful

alkenes which are used to make polymers

conditions for cracking

- 600-700C

- Silica (SiO2) or alumina (Al2O3) catalyst

describe cracking process

- hydrocarbon is heated until vapourised

- it breaks down when it comes into contact w catalyst

- this produces mix of short chain alkanes and alkenes

cracking diagram

ADD DIAGRAM

fuel

is a substance that, when burned, releases heat energy

combustion

combustion is a rapid reaction between a substance and oxygen that releases heat and light energy

why do hydrocarbon make good fuels

- bc when you burn them in oxygen

- they give out lots of energy

how could u describe the reaction when you burn hydrocarbons in oxygen

very exothermic

products of complete combustion

carbon dioxide and water

when does incomplete combustion happen

When there is not enough oxygen

products of incomplete combustion

- u always get water in both types combustion

- u can also get C (soot) or CO or both

why is CO toxic

it binds to your red blood cells and prevents oxygen transport around your body

could lead to fainting/coma/death

how can sulfur dioxide be produced from crude oil fractions

sulfur dioxide comes from sulfur impurities in the hydrocarbon fuels

when are nitrogen oxides created

when temp is high enough for nitrogen and oxygen in air to react

where are nitrogen oxides often created

car engines

what does nitrogen oxides include

nitrogen monoxide and nitrogen dioxide

how do nitrogen oxides and sulfur dioxide form acid rain

- when they mix with water vapour in clouds

- they form dilute sulfuric acid and nitric acid

- acid rain then falls

why is acid rain bad

- causes lakes to become acidic

- many plants + animals die