organic chemistry

Question 1

Formation of crude oil

Answer 1

Made from remains of marine plants and animals - mostly plankton - that died millions of years ago

Remains sank to bottom of sea and were buried by layers of sand and mud, preventing them from rotting

Layers gradually became sedimentary rock

Over millions of years, layers of rock built up increasing the heat and pressure, breaking remains into CRUDE OIL.

Question 2

Crude oil is a mixture of molecules called what?

Answer 2

Hydrocarbons

Question 3

what is a hydrocarbon (definition)

Answer 3

Hydrocarbons are molecules made up of hydrogen and carbon atoms only

Question 4

what is one hydrocarbon in crude oil

Answer 4

methane

Question 5

methane formula

Answer 5

CH4

Question 6

what kind of resource is crude oil and where found

Answer 6

finite, found in rocks

Question 7

besides methane, what other hydrocarbon is found in crude oil

Answer 7

ethane

Question 8

what do scientists call hydrocarbons like ethane and methane

Answer 8

alkanes

Question 9

what is the general formula of alkenes

what this means

Answer 9

CnH2n+2

this means that if we know the numb of carbon atoms in the alkene (n), then we can calculate the number of hydrogen atoms
to do that ,we calculate the number of hydrogen atoms by 2 and then add 2

Question 10

propane is an alkene with 3 carbon atoms.
work out the number of hydrogen atoms
then write the formula

Answer 10

8

formula = C3H8

Question 11

what are alkanes and why

Answer 11

saturated molecules

because the carbon atoms are fully bonded to hydrogen atoms

(for my own info, alkenes are a family of hydrocarbons)

Question 12

what are the first four alkanes

Answer 12

methane
ethane
propane
butane

Question 13

methane structure

Answer 13

H
            l
      H - C - H
             l
            H

Question 14

Ethane structure

Answer 14

H    H
            l      l
      H - C - C - H
             l     l
            H    H

Question 15

Propane structure

Answer 15

H    H   H
            l      l     l
      H - C - C - C - H
             l     l     l
            H    H   H

Question 16

Butane structure

Answer 16

H    H   H   H
            l      l     l    l
      H - C - C - C - C - H
             l     l     l     l
            H    H   H   H

Question 17

what does viscosity tell us

fluids with a high viscosity flow …

fluids with a low viscosity flow ….

Answer 17

the thickness of a fluid

slowly

quickly

Question 18

as the size of hydrocarbons increase, what happens to the viscosity of the molecules

so very long chains of hydrocarbon flow very …..

but short chains flow…./

Answer 18

they get more viscous

slowly - they r extremely viscous

quickly

Question 19

what does flammability tell us

Answer 19

how easily a hydrocarbon combusts (burns)

Question 20

how flammable are short chain hydrocarbons

Answer 20

extremely flammable

Question 21

what gas is used in bunsen burners

Answer 21

methane

Question 22

as the size of hydrocarbons increase, the molecules get more or less flammable

Answer 22

less

Question 23

are long chain hydrocarbons difficult to burn

Answer 23

yes.

Question 24

what is the boiling point

Answer 24

the temp at which a liquid turns to gas

Question 25

do short chain hydrocarbons have low or high boiling points

Answer 25

low

Question 26

the first four alkenes are gases at room temp, why

Answer 26

because they all have boiling points which are lower than room temp

Question 27

when do hydrocarbon fuels release energy

Answer 27

when combusted (burned) during combustion, thecarbon and hydrogen atoms in the fuel react with oxygen. The carbon and hydrogen are oxidised

Question 28

when hydrocarbon fuels release energy when combusted, if this oxygen is unlimited then what does it produce and what is this called

Answer 28

carbon dioxide and water called complete combustion

Question 29

what do we have to do in order for hydrocarbons to be useful

Answer 29

seperate them

Question 30

how do we separate hydrocarbons

Answer 30

using fractional distillation

Question 31

In fractional distillation, crude oil is separated into ..... Fractions contain hydrocarbons with a similar number of ...... .....

Answer 31

fractions | carbon atoms

Question 32

where does fractional distillation take place in

Answer 32

very large columns which are found in oil refinaries

Question 33

steps of fractional distillation of crude oil

Answer 33

Crude oil heated to high temp, causing it to boil - all hydrocarbons evaporate and turn into gas crude oil vapour is then fed into fractional distillation column column is hotter at bottom and cooler at top hydrocarbon vapours rise up column hydrocarbons condense (turn to liquid) when they reach their boiling point, aka they turn back to liquid Liquid fractions are then removed remaining hydrocarbons keep moving up column These condense when they reach their boiling points

Question 34

very long chain hydrocarbons have what

Answer 34

very high boiling points

Question 35

in fractional distillation, long chain hydrocarbons have high boiling points. Where are they removed from?

Answer 35

From the bottom of the column

Question 36

short chain hydrocarbons have low boiling points. in fractional distillation, these do not condense. Where are they removed from and as what

Answer 36

removed from the top of the column as gases

Question 37

Fractional distillation produces what which contain what

Answer 37

fractions which contain hydrocarbons with a similar number of carbon atoms

Question 38

some fractions are used as fuels. Give some examples

Answer 38

petrol and diesel to fuel cars or liquified petroleom gas in camping stoves

Question 39

Some fractions are used as feedstock for the petrochemical industry. What is a feedstock

Answer 39

A chemical used to make other chemicals

Question 40

general formula of alkanes

Answer 40

CnH2n+2

Question 41

between the carbon atoms, what kind of bond do alkanes have

Answer 41

alkanes only have single covalent bonds between the carbon atoms

Question 42

name one reason as to why long-chain hydrocarbons do not make good fuels

Answer 42

because long chain hydrocarbons are not very flammable this is a problem because there is such a high demand for short-chain hydrocarbons to be used as fuels

Question 43

to solve our problem of there being such a high demand for short chain hydrocarbons to be used as fuels since long chained hydrocarbons are not flammable, what should be done

Answer 43

convert long chain hydrocarbons into shorter chain hydrocarbons TO DO THAT WE USE A PROCESS CALLED CRACKING!

Question 44

What happens in cracking...?

Answer 44

A long-chain alkane is broken down (cracked) to produce smaller, more useful molecules

Question 45

conditions for cracking..../what are the two ways we can carry out cracking... one of them is called catalytic cracking, what happens here

Answer 45

In catalytic cracking, we use high temperature and a catalyst (job of the catalyst is to speed up the reaction)

Question 46

conditions for cracking..../what are the two ways we can carry out cracking... another of them is called steam cracking...what happens here?

Answer 46

In steam cracking, we use high temperature and steam

Question 47

what does cracking make

Answer 47

hydrocarbons called alkenes

Question 48

what kind of bond do alkenes have between two carbon atoms

Answer 48

alkenes have a double covalent bond between two carbon atoms

Question 49

alkenes are very useful molecules. why?

Answer 49

Firstly, alkenes are used to make chemicals called polymers Alkenes are also used as a starting material for other useful chemicals as well

Question 50

are alkenes more or less reactive than alkanes

Answer 50

Alkenes are MORE reactive than alkanes

Question 51

One key fact about alkenes is that they are more reactive than alkanes. We can use this to test for alkenes and it is really important to learn this test....

Answer 51

we test for alkenes using bromine water which is orange. If we shake our alkene with bromine water, then the bromine water turns COLOURLESS

Question 52

ALSO remember to learn all the molecular formulas and stuff for alkanes and alkene like ethene/ethane etc

Answer 52

yes