C6.2 Alkanes Alkenes

Question 1

Alkanes

HOW ARE THEY LART OF A HOMOLOGOUS SERIES.

Answer 1

Saturated hyrdocarbins

• form a homologous series because they have features in common
• follow a general formula = Cn H2n +2
• single covalent bonds used = saturated
• differs by a CH2 group

They do combust to form co2 and water, but also incomplete combustion to form carbon monoxide and water.

Carbon, soot carbon particulates can also be produced

Question 2

Alkenes

How they follow a homologous series

Is methene possible?

Answer 2

Alkenes homologous because

• follow generalnformula = Cn2n
• have a functional group = where a bind of elements determine its properties. ( c- c double bind)
• differ by cH2

Unsaturated, the c-c double bind can break and form binds with other atoms

NO METHEN PE POSSIBLE

Remmeber at all times a carbon must bind with 4 things

Question 3

How to test for alkenes

Answer 3

@) add bromine water, alkene will decolourise the bromine water if it is alkene (this is halogenstion) and because they can open a bond.

Goes from krsngebtincolourless ifnalkene

B2 + c2h4 = b2c2h4
TBIS dibromerhane
Methane because all of it is full now, cnnh2n + 2

Question 4

Cracking

Answer 4

When alkene becomes alkene and ethene, used sfter seprsting alkanes in crude oil

1) need high temp and catalysts

Happens so we can make more shorter chain alkanes which are more easy to ignite and in higher demand. Alekenes dna then be euthernjyrdorgenwted to form alkanes or used in addition polymerisation

Question 5

What makes a homologous series homologous

Answer 5

1) generals Formular
2) functional group / react in similar ways
3) differ by a ch2 groups

2 is basically 2 things

Question 6

What is a functional group?

Answer 6

Atom, groups of atoms, type of bond that determines the chemical characteristic reactions that happen of an organic compound

Question 7

What is difference between displayed , molecular and structural Formular ?

Answer 7

1) displayed is draw it out properly
2) structural is based on how it looks ordered like that
3) molecular is just like c4h10

Question 8

What can the ability of having a CARBIN double in aliens allow them to do with hydrogen and what catalyst is needed

Answer 8

Addition resctions in the presence of hydrogen with nickel catalyst to for, an alkane. (Hydrogenation maybe?)

Question 9

Alcohols
What can thy do to form something else

What do they react with to make an ester

Answer 9

1) cn2n+1 OH, Functional OH
2) OH oxidised means alcohols can be oxidised To firm carboxylic acids.
3) also take part in combustion
4) alcohol + caroboxylic = ester

Question 10

Organic

Answer 10

Compounds means it has carbons in it

Question 11

Carboxylic acids

Is there a double bind?
How are they made
What are their reactions typical like
What do they join with to make an Ester or amide

Answer 11

Homologous 
1) cool functional 
2) formula = cn-1 2n-1 Cooh 
3) remember double bind c with o
4) oxidise alcohol to make it 
5) reacts the same way acids so,
6) alcohol + cabrixhlic = Ester
Amine + carbiyckic = amide

Question 12

How are carboxylic acids made?
Also understanding
What is the oxising agent (2 things)

Also what happens in the colour change and why!!

Answer 12

• basically carboxylic acids become oxidised to form an alcohol so they gain oxygen
  1) for example, an oxising absent of potassium manganite (7) can be added to ethanol. This oxising agent IS acidified with a little DILUTE SULFURIC ACID.
  2) then warm it in a water bath
  3) then a colour change occurs because manganite (7) ions are purple and become REDUCED to pale pink managnaes (11) ions when the acidified potassium managnateb(7) oxidises ethanol to ethanol companies acid

Purple managnatebions become reduced into pale pink manganese (2) ions.

Question 13

As carboxylic acids are typical of acids what reaction do they undertake?

How do you name the salts with carboxylic acids?

Answer 13

1) metals with acid = salt + hydrogen gas
2) acid+ alkali = salt + water
3) acids + metal carbonate = salt + water + CARBIN dioxide

Metal + say Ethan + OATE

so potassium methanoate for example

Question 14

Where does crude oil come from

It is our main source if?

What makes it a non renewable source ?

Answer 14

Buried remains of marine organisms lived millions of years ago making it a fossil fuel . Over millions years under high temp and pressure they become crude oil which can be extracted

Hyrdocarbins

It is being used faster than made

Question 15

What happens if there are more CARBOn atoms in an alkane ? (Important 3)

Answer 15

1) the stinger the intermolecular forces as there are more contact pints and thus more intermolecular
2) thus higher boiling and melting
3) also bigger molecules ofc

Question 16

How is crude oil extracted 6 marker mr choo

What about some of the gasses

Answer 16

1) crude oil is heated and a temperature gradient is thus established (this is where it’s hotter at the bottom and cold at the top)
2) the alkanes evaporate and rise up the column
3) the alkane vapours cool as they rise up the colouring
- different alkanes will have different boiling points
4) once they reach a part where the temperature is less than the boiling pint (or ince they hit their feeding pint ), they CONDENSE into liquid
5) these are then collected in separate tanks , these separate sections are called fractions which contain many alkanes of similar band

2) refinery gases have the lowest boiling pints and reach the top without even condemning snd Exit in gas form. Bitumen similarly is almost solid at rt

Again for fun
1) crude oils are heated and temp gradient established

Question 17

Why is fractionally distalkrion used
What is the use of crude oil?
Why are small alkanes more desierbwle ? (3) IMPORTSNT
What are big alkanes used for then

Answer 17

)
electricity heating , fuel for transport, raw materials to make plastics infrastructure

2) require less oxygen, so combust completely, less energy to ignite = HIGHLY FLAMMABLEM, also flow eastern
3) infrastructure and cracking to make alkenes and alkanes and thus

Question 18

What does cracking Dom?

What is needed to make it happen ? What does allow it to do?

Why is it done

Answer 18

Chemical reaction that converts large alkane molecules into smaller alkanes and alkenes
Octane c8h18-> Propene c3h6 snd pentane c5h12

2) high tem 600-700 and hot catalyst of alumina or silica , which MAKE THE CIVALENT BINDS BREAK
3) to make smaller alkanes which are higher in demand and alkenes ti make plastics in ploymer form

Question 19

Alkene used for?

Answer 19

Plastics
Hydrogenation (back to alkanes
Hydration?

Question 20

How does practices of making paraffin Hallen?

Answer 20

1) liquid paraffin is heated into gas form so it can react with the ctaksydt (this is thermal decomposition)
2) now you get an alkane as liquid and alkene as gas as alkanes will always have higher intemroelfulwrnbinds due to them being able to be stacked on each other

Question 21

Additon polymerisation
What is it
What does it require
What need to start it aswell

Answer 21

1) additon polymers are made from many unsaturated monomers that joint together to make a polymer , the. Kromer sundergi additon reactions to join
2) will usually require high pressure and catalyst
3) open brackets and binds, n
4) an initiator chemical that starts the chain off

Use water bath as they flammable, fume hood and googled if needed

Question 22

Dna structure and bindings

Answer 22

Nucleotides join to make dna

2) deoxyribiose of one joins with the phosphate if one on top
3) hydrogen binds formed between comolentwry based

Question 23

Amino acids for Proteinen

Answer 23

20
2) has functional group on each end so as monomers they can undergo condensation polymerisation still
Amine Gounods nh2
Amide group is conh

And polymerisation of amino acids would be -( nh-block-co)-
Basically amino acids also have carboxylic acids group at the others side

Question 24

Carbohydrates, difference between simple sugars and complex carbs ?

Answer 24

1) compounds of carbon, hydrogen and oxygen USED BY LIVING THINGS TO PROVIDE ENERGY
2) simple SUgars deoxyribios and sucrose
Complex are starch, which are made up of other simple sugars such as glucose

Question 25

Condensation reaction / polymerisation

What do monomer molecules require in these polymerisation ?

What is required again for this to happen ?

Answer 25

Two molecules react to make one larger molecule and one smaller molecules, and it’s called condensation as smaller one often water

1) carboxylic + alcohol = Ester group coo
2) carboxylic + Amine group = amide group conh

3) for it to have two functional groups on each side so that it can react alternatively with another monomer with two, or in the case of amino acids that have two different, works aswell (carboxylic snd Amine )

4) polyester made from dicarboxylic acid and a dialcohol , polyester because of the many Ester groups made
5) polyamide made from amino acids, dicsrboxylic acids with an Amine with two Amine groups (dismine) , culled polyamide because of many amide groups

Ctaksyt and high temp and pressure

Question 26

Nylon making

Answer 26

1) . In water out diaminohedsne and other mix dihedsnedioyl in organic solvent
2) pour one on top and retrieve the nylon using tweezers

Question 27

H fuel cells

1) how does a basic cell work ? (Including when it dies)

Answer 27

1) exothermic resctions in the cell snd that develops a potential difference between two ends, and if connected to a circuit current flows through the cell. This continues until one of the reactants are used up meaning the cell is now “flat” and csn’t produce s pd.

Question 28

How does a h fuel cell work then ?

Answer 28

Produces electricity through a chemical resction between fuel and oxygen without the need of combustion

1) the overall reaction hydrogen - oxygen is water vapour.
- this an endothermic reaction as it releases energy

However this happens in two reactions on two ends of the cell

Question 29

How does the hydrogen react first

Answer 29

Hydrogen molecules lose electrons to become ions
2H2-> 4H+ + 4e-

Then the ions pass through a Proton exchange membrane to the other side of the fuel cell, allowing for electrons to travel to the external circuit in the other side

2) hydrogen ions react with oxygen and electrons on the other side to form water
- 4H+ +4e- +o2-> 2H2o

Now this flow of electrons through an external cihit from snide to cathode is current

Question 30

Again summarised + what about snide cathode ?

Answer 30

Anode and cathode are actually negative and positive here , oxygen dtsjodenhydrigen snode….

1) hydrogen at the ANODE loses electrons to become positive
2) hydrogen ions move across electrolyte to the cathode
3) the electrons move through an external circuit sn arrive at the cathode
4) at the catjide hydrogen + electrons + oxygen make water
This is thus redox, oxidation ar anode , reductionist cstjide

Question 31

What are advantages of h fuel cells

Compared to batteries?

Answer 31

1) no pollutants are made
2 effienctn
3) but expensive to adapt technology to meet it, also hydrogen is hard to extract and store

1) refuel time much faster, lighter, less emissions but more expensive

Question 32

General Formular for polymerisation condensation

Answer 32

2n-1

Question 33

Addition vs condensation

Answer 33

1) additon vs consensrion
2) one monetär vs 2 monomers used
3) one vs 2 products
3) from sleekness s diol + carboxylic
5) Ester linkage vs hydrocarbon
7) cstlsyst and temp