4.1 Basic Concepts and Hydrocarbons (completed)

Question 1

What is the stem name and side chain name for these number of carbon atoms?
1
2
3
4
5

Answer 1

Meth; Methyl 
Eth; Ethyl
Prop; Propyl
But; Butyl
Pent; Pentyl

Question 2

What is the stem name and side chain name for these number of carbon atoms?
6
7
8
9
10

Answer 2

Hex; Hexyl 
Hept; Heptyl
Oct; Octyl
Non; Nonyl
Dec; Decyl

Question 3

What is the general formula for alkanes?

Answer 3

Cn H2n+2

Question 4

What is displayed formulaof ethane?

Answer 4

Draw a compound showing all bonds and elements present
       H    H
        |      |
H - C - C - H
        |      |
       H    H

Question 5

What is the structural formula of butane?

Answer 5

CH3CH2CH2CH3

Question 6

What chain should you use when naming organic compounds?

Answer 6

The longest chain

Question 7

What are cycloalkanes and what is their formula?

Answer 7

Carbon atoms joined up in a ring with formula CnH2n

Question 8

Do alkanes and cycloalkanes have the same properties?

Answer 8

Yes

Question 9

What is a hydrocarbon?

Answer 9

An organic molecule that contains hydrogen and carbon only

Question 10

What is a homologous series?

Answer 10

A series of organic compounds with same general formula with the same functional group but each successive member difference by CH2

Question 11

What is the structure of alkanes?

Answer 11

Single covalent bonds,
Sigma bonds,
Tetrahedral shape,
109.5°

Question 12

What is the equation for complete combustion?

Answer 12

Alkane+ Oxygen → Carbon Dioxide + Water

Balance carbons, then hydrogen, then oxygen

Question 13

What is the equation for incomplete combustion?

Answer 13

Alkane+ Oxygen → Carbon Monoxide + Water

In very limiited conditions soot (C) is formed along with water

Question 14

Why is incomplete combustion of hydrocarbon fuels potentially dangerous?

Answer 14

Carbon monoxide is poisonous and can kill you

To avoid this a carbon monoxide alarm can be installed

Question 15

What is cracking?

Answer 15

Breaking down large alkanes into a smaller alkane and an alkene

Question 16

What are two possible products formed when cracking pentane?

Answer 16

C5H12 → C3H6 + C2H6

C5H12 → C3H8 + C2H4

Question 17

Why do branches in alkane chains lower the boiling point?

Answer 17

Branches cause less contact between molecules
Therefore weaker induced dipole dipole forces
Therefore lower boiling point

Question 18

What are the conditions needed for free radical substitution?

Answer 18

UV light

Question 19

What are the three stages within free radical substitution?

Answer 19

Initiation
Propagation
Termination

Question 20

What is heterolytic fission?

Answer 20

A covalent bond is broken and both electrons are retained by one of the bonding atoms
XY → X+ + Y-
XY → X- + Y+

Question 21

What is homolytic fission?

Answer 21

When a covalent bond is broken and each atom retains one electron creating two free radicals
XY → X• + Y•

Question 22

What is the initiation stage of free radical subsitution of chlorine with ethane?

Answer 22

Cl2 → Cl• + Cl•

Question 23

What is the propagation stage of free radical subsitution of chlorine with ethane?

Answer 23

Cl• + C ₂H ₆ → C2H5• +HCl

Cl2 + C2H5• → Cl• + C2H5Cl

Question 24

What is the termination stage of free radical subsitution of chlorine with ethane?

Answer 24

Cl• + Cl• → Cl2
Cl• + C2H5• → C2H5Cl
C2H5• + C2H5• → C4H10

Question 25

What would happen if in free redical substitution of bromine and ethane bromine was added in excess?

Answer 25

Multiple substitution of bromine groups onto the ethane molecule

Question 26

What are alkenes?

Answer 26

A homologous series of unsaturated hydrocarbons that have the general formula CnH2n

Question 27

What makes a hydrocarbon unsaturated?

Answer 27

At least one carbon carbon double bond

Question 28

What is the bond angle and structure in C=C bonds?

Answer 28

120° due to overlap of p-orbitals giving trigonal planar

Question 29

What is a pi bond compared to a sigma bond?

Answer 29

Pi bonds are formed with p orbitals overlapping and are involved in C=C bonds. Pi bonds are weaker and explains why alkenes are more reactive

Question 30

What is stereoisomerism?

Answer 30

Molecules have the same molecular formula but occupy different positions in 3-dimensional space

Question 31

Why are E/Z isomers formed?

Answer 31

Found in some alkenes due to the lack of rotation around the C=C bond

Question 32

What is the difference in E/Z isomers?

Answer 32

E (entgegen) the priority is on opposite sides Z (zusammen) the priority is on the same side

Question 33

What are cis trans isomers?

Answer 33

A special case of E/Z isomers where the groups on each side of the double bond is the same Z, cis E, trans

Question 34

What is hydrogenation of an alkene and what are the conditions?

Answer 34

``` Adding hydrogen to break the C=C to produce an alkane Nickel catalyst (also pt) 200°c 1000kPa (1atm) ```

Question 35

What is an electrophile?

Answer 35

An electron pair acceptor

Question 36

What is electrophillic addition?

Answer 36

When alkenes are attacked by electrophiles and undergo addition reactions

Question 37

What is showed by curly arrows in mechanisms?

Answer 37

Transferrence of electron pair | Should start touching a bond and end where the electrons will be (bond or atom)

Question 38

In the first step of an electrophilic substitution where do the curly arrows go?

Answer 38

From C=C bond to δ+ element | From covalent bond in electrophile to δ- element

Question 39

In the second step of an electrophilic substitution where do the curly arrows go?

Answer 39

From electron lone pair on negative halogen to + carbon

Question 40

How can you test for alkenes?

Answer 40

Alkenes decolourise bromine water from orange to colourless

Question 41

What is the reaction to make an alcohol from an alkene?

Answer 41

Alkene + H2O → Alcohol Steam 320°C Concentrated Phosphoric Acid Catalyst

Question 42

What is Markownikoff’s rule?

Answer 42

In addition reactions, hydrogen will add onto the carbon with the most hydrogen already on it

Question 43

What is a primary secondary and tertiary carbocation?

Answer 43

Primary has one carbon bonded to the central carbon atom Secondary has two Tertiary has three

Question 44

Which carbocation is the most stable?

Answer 44

Tertiary

Question 45

What are addition polymers?

Answer 45

Long hydrocarbon chains from from alkenes | All atoms in the original alkene are used

Question 46

How are addition polymers formed?

Answer 46

Double carbon bomb breaks, | Central carbon atoms forms two bonds to the next monomer

Question 47

Why is it difficult to dispose of polymers?

Answer 47

They are fairly inert as it is basically a very large alkane Resistant to chemical attack and non-biodegradable Unreactive to most chemicals and bacteria If discarded they add to the landfill problem

Question 48

What are the advantages and disadvantages of burning polymers to dispose of them?

Answer 48

Burning saves on landfill sites and produces energy | Some chlorinated polymers produce toxic fumes (HCl)

Question 49

How are polymers disposed using feedstock?

Answer 49

Use the waste for the production of useful organic compounds (feed stock) New technology can convert waste into hydrocarbons Hydrocarbons can then be turned back into polymers

Question 50

Name the process used to obtain kerosene from crude oil

Answer 50

Fractional distillation | Which works because fractions have different boiling points

Question 51

Why are straight chain isomers converted by the petroleum industry into branched chain isomers?

Answer 51

Branched chains have more efficient combustion

Question 52

What is a free radical?

Answer 52

Species with an unpaired electron

Question 53

What is meant by the term fractional distillation?

Answer 53

Separation by differences in boiling point

Question 54

Why has the polymer of C2F4 very inert?

Answer 54

C-F bonds have high bond enthalpy

Question 55

What should have the lowest number when naming compounds, methyl group or alcohol group?

Answer 55

Alcohol

Question 56

What does the reaction of propanol with NaCl, H2SO4 produce?

Answer 56

Chloropropanal NaHSO4 H2O

Question 57

What are aliphatic compounds?

Answer 57

An open carbon chain - not aromatic | e.g. butane

Question 58

What are alicyclic compounds?

Answer 58

Aliphatic compounds bonded in a ring structure | e.g. cyclopentane

Question 59

What are aromatic compounds?

Answer 59

Compounds formed from a benzene ring | e.g. phenol

Question 60

What is the definition of a pi bond?

Answer 60

Sideways overlap of p orbitals

Question 61

What is the definition of a sigma bond?

Answer 61

Overlap of orbitals between atoms