Oil refining, Fules and Fhermochemistrey Flashcards

fossil fules are formed from the remains of plants and animals that lived millions of years ago

a mixture of hydrocarbons-primarliy methane

1. animal waste and dead plants allowed to be decomposed by anaerobic bacteria producing methane
   2.naturally prouced in slurry pits,coal mines and refuse dumps

methane is a very good fuel

accidents have occoured in mines as methane forms an explosice mixture with air and exposives have occoured

its one of the leading gasses that causes greenhouse effect leading to global warming

crude oil is a type of oil that is a mixture of many different hygrocarbons

a distillation that is used to separate crude oil into its component hydrocarbons based on their specific molecular mass/boiling point

The crude oil at base column is heated and mostly becomes a vapour
moved up through the column, the temperture decreases going up. The different factions of hydrocarbons condense into a liquid once they cool below their specific cooling point and are collected on a specific tray
the larger molecules wiht higher boiling points are collected at lower levels. The smaller molecules with lower boiling points are collected at higher levels

Their boiling points
Their molecular mass

Refinery Gas C1-C4 -Domestic gas (LPG)

Light gasoline C5-C10 -Petrol for cars

Naphtha C7-C10 -Petrol for cars
-Feedstock for the petrochemical industry to make plastics, solvents,detergents

Kerosene Paraffin Oil
C10-C14 -Fuel for jet aircraft
-Oil for home central heating

Gas Oil (Diesel oil) C14-C49
-Diesel for vehicles
Lubricant for engines Residue
C35 and higher
Bitumen for road surfacing, roofing and waterproofing

this is the fraction left over as a liquid at the bottom of the fractionating column and the other more volatile fractions turn to gasses and travel upwards

liquid petroleum gas

propane and butane mixture
it is sold as domestic gas for heating and cooking

mercaptans are sulfur containing compounds
they are added to natural gas(methane) and liquid petroleum gas to give them a unpleasent smwll to warn of gas leaks

1. light gasoline

2. Naphtha

a mixture of different hydrocarbons,mostly chain lenght C5-C10 alkanes

In the engine of a car, a mixture of petrol and oxygen is ignited by spark plugs
the ‘explosion’ provides power to turn the wheels

The premature ignition of he petrol-air mixture before a spark is produced by spark plugs.
it results in loss of power and damage the engine

petrol containing long unbranched straight chained alkanes eg heptane

measure of a tendency of a fuel to resist auto ignition

lenght of chain- shorter chain= better octane number
degree of branching- the more branched= the higher octane number
cyclic structure- cyclic compounds hacr a higher octne number than straight chain

two refrence compounds are used
Heptane has a octane number of 0
2,2,4-teimethylpentane has a octane number of 100the performance of the fuel is compared with know mixtures of heptane and 2,2,4 trimethylpentane and given a suitable octane number

lead is harmful to the enviorment and peoples health
lead poisond the catalytic converter in cars

isomerisation
dehydrocyclisation
catalytic cracking

Isomerisation involves the changing straight chain alkanes into branched compounds with the same molecular formula but different structural formula.

straight chain alkanes are heated causinf chains to break

dehydrocyclisation is the use of a catalyst to cause a straight chained hydrocarbon lose its hydrogen forming a ringed compound

hygrogen is also produced
hydrogen can be used for
-ammonia production
-make margarine
-a fuel

catalytic creacking involves using heat and a catalyst to break down lond chained hydrocarbons for which there is low demand into shorter chained molecules for which there is a greater demand

( you always get an alkene at least)

alkenes are also formed, alkenes are widly used in the petrochemical industry to make plastics

addition of compounds that contain oxygen to the petrol

a. methanol, ethanol

b.MTBE (metyl tert-butyl ether)

these compounds increase the octane number of the poetrol

petrol containing oxygenates also give rise to much less pollution

-steam reformation of natural gas

-electrolysis of water

-dehydrocyclosation of hydrogen

CH4 + H2O -> 3H2 + CO

hydrogen gas collecrs at the negative electrofe/cathode

2H2O-> 2H2 + O2

produces hydrogen gas as a bi-product

manufature of ammonia, known as tge haber process, ammonia is used in fertilisers,cleaners and bleaches

hydrogenation of vegtable oil to make margarine

potetial to use as a fuel

hydrogen is a clean fuel- water is the only product of its combustion

hydrogen burns efficiently as a fuel- it has a high kilogram calorific value: a lot of energy is given our per kg burned in oxygen

hydrogen is explosive with oxygen- problems with storage and transportation

ΔH

a reaction that produces and gives out heat to its surroudings

it has a negative ΔH value and produces an increase in temperture

a reaction that takes in heat from its surounddings

has a postive ΔH valur and decreases in temperture

heat of formation is the heat change that ocoours when one mole of a substance is formed from elements in standard states

(right hand side cannot be changed)

the heat change that occours when one mole of a substance os completely burned in excess oxygen

(1 mole on left hand side)

CO2 and H2O

a bomb calorimeter

a known mass of the substance is places in the crucibe in the bomb.

bomb is placed in a known volume of water.

the substance is ignited electrically and allowed to burn in excess oxygen

the change in temperture in water is recorded

heat produced is calculated using formula m x c x ΔH

the heat produced for one mole is calculated

kilogram calorific value is the heat energy produced when 1 Kg of a fuel is burned completely in excess oxygen

convert 890 Kj mol-1 calculate the kilogram calorific value of methane

divide 16/1000 to get per kg.

890 divide by 0.016 and multiply by 1 to get -55625

methane has a very high kilogram calorific value- a lot if energy is given out per kg burned in oxygen

methane is a pure subtance and burns with a clean flame

bond energy is the average energy required to break one mole of a particular colvalent bond and to sseparate the netrual atoms completely from eachother

heat of reaction is the heat change that occours when the number of moles

given in a balanced equation react completely

hess's law sates that if a chemical reaction takes place in a number of stages, the sum of the heat changes in seperate stages is equal to the heat change if the reaction is carried out in one stage

A+b+C+D = a -> D

The heat change that occurs when 1mole of H+ ions from and acid reacts with 1 mole of OH- ions from a base

it is always exothermic (always negative ΔT value)

Using a graduated cylinder add hydrochloric acid to a polystyrene cup and add sodium hydroxide to a separate polystyrene cup.

Record the temp 1( if the two are not equal, calculate their average)

Record the max temperature obtained T2. Record the rise in temperature and calculate the heat for the reaction using m X c X ΔT and hence the heat of reaction/netralisation

addition of oxygenates

Dertimining the heat of reaction of hydrochloride acid with sodium hydroxide ie.heat of neutralisation

They are excellent insulators and will only allow a minimal heat loss to surroundings

they have a negligible heat compacity- they will absorb a neglugible amount of heat away from the reaction

Advantage a pipette is more accurate than a graduated cylinder

Disadvantage a pipette is very slow to measure out solutions

An average temperture of the two solutions is essential

the temperture rises; exothermic reactions have a rise in temperture

to distribute the heat evenly and take accurate temperture readings

to ensure the the solutions react completely

-Once the solutioms are mixed quickly cover the polystyrene cup with a lid to avoid heat loss to surroundings

-ensure no splashing and loss of volume of liquid occours-leads to innacurate results

-a sensitive thermometer is used ( one that reads to at least 0.1C )

the temperture of the solutions after mixing will be greater than room temperture, heat will be lost to the surroundings

concentrated solutions are used to obtain a significant rise in temperture

a larger temperture rise is easier to measure accuratelu and will have less percentage error

as concentrated solutions of HCl and NaOH are being used, they are corrosive and cause burns

saftey glasses are worn

gloves and lab coat are worn

-more insulation- a more accurate rise in temperture would be recorded

three times the volume produces three times the heat

but this heat spreads itself throughout three times a greater volume.

therefore the tempertur rise is the same

the amount of heat required to raise the temperture of 1 kg of a substance by 1 kelvin

(m X c X ΔT)

C (m x c)= (total heat capacity)

heat produced (step 2)/ number of moles of acid (step 1)