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Chemistry :) > 4.1 Basic Concepts and Hydrocarbons (completed) > Flashcards

4.1 Basic Concepts and Hydrocarbons (completed) Flashcards

4.1.1 Basic organic chemsitry 4.1.2 Alkanes 4.1.3 Alkenes

1
Q 
What is the stem name and side chain name for these number of carbon atoms?
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A 
Meth; Methyl 
Eth; Ethyl
Prop; Propyl
But; Butyl
Pent; Pentyl
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2
Q 
What is the stem name and side chain name for these number of carbon atoms?
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A 
Hex; Hexyl 
Hept; Heptyl
Oct; Octyl
Non; Nonyl
Dec; Decyl
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3
Q

What is the general formula for alkanes?

A

Cn H2n+2

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4
Q

What is displayed formulaof ethane?

A 
Draw a compound showing all bonds and elements present
       H    H
        |      |
H - C - C - H
        |      |
       H    H
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5
Q

What is the structural formula of butane?

A

CH3CH2CH2CH3

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6
Q

What chain should you use when naming organic compounds?

A

The longest chain

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7
Q

What are cycloalkanes and what is their formula?

A

Carbon atoms joined up in a ring with formula CnH2n

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8
Q

Do alkanes and cycloalkanes have the same properties?

A

Yes

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9
Q

What is a hydrocarbon?

A

An organic molecule that contains hydrogen and carbon only

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10
Q

What is a homologous series?

A

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

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11
Q

What is the structure of alkanes?

A

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

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12
Q

What is the equation for complete combustion?

A

Alkane+ Oxygen → Carbon Dioxide + Water

Balance carbons, then hydrogen, then oxygen

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13
Q

What is the equation for incomplete combustion?

A

Alkane+ Oxygen → Carbon Monoxide + Water

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

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14
Q

Why is incomplete combustion of hydrocarbon fuels potentially dangerous?

A

Carbon monoxide is poisonous and can kill you

To avoid this a carbon monoxide alarm can be installed

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15
Q

What is cracking?

A

Breaking down large alkanes into a smaller alkane and an alkene

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16
Q

What are two possible products formed when cracking pentane?

A

C5H12 → C3H6 + C2H6

C5H12 → C3H8 + C2H4

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17
Q

Why do branches in alkane chains lower the boiling point?

A

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

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18
Q

What are the conditions needed for free radical substitution?

A

UV light

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19
Q

What are the three stages within free radical substitution?

A

Initiation
Propagation
Termination

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20
Q

What is heterolytic fission?

A

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

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21
Q

What is homolytic fission?

A

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

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22
Q

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

A

Cl2 → Cl• + Cl•

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23
Q

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

A

Cl• + C ₂H ₆ → C2H5• +HCl

Cl2 + C2H5• → Cl• + C2H5Cl

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24
Q

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

A

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

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25
Q

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

A

Multiple substitution of bromine groups onto the ethane molecule

26
Q

What are alkenes?

A

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

27
Q

What makes a hydrocarbon unsaturated?

A

At least one carbon carbon double bond

28
Q

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

A

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

29
Q

What is a pi bond compared to a sigma bond?

A

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

30
Q

What is stereoisomerism?

A

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

31
Q

Why are E/Z isomers formed?

A

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

32
Q

What is the difference in E/Z isomers?

A

E (entgegen) the priority is on opposite sides

Z (zusammen) the priority is on the same side

33
Q

What are cis trans isomers?

A

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

34
Q

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

A 
Adding hydrogen to break the C=C to produce an alkane
Nickel catalyst (also pt)
200°c 1000kPa (1atm)
35
Q

What is an electrophile?

A

An electron pair acceptor

36
Q

What is electrophillic addition?

A

When alkenes are attacked by electrophiles and undergo addition reactions

37
Q

What is showed by curly arrows in mechanisms?

A

Transferrence of electron pair

Should start touching a bond and end where the electrons will be (bond or atom)

38
Q

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

A

From C=C bond to δ+ element

From covalent bond in electrophile to δ- element

39
Q

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

A

From electron lone pair on negative halogen to + carbon

40
Q

How can you test for alkenes?

A

Alkenes decolourise bromine water from orange to colourless

41
Q

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

A

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

42
Q

What is Markownikoff’s rule?

A

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

43
Q

What is a primary secondary and tertiary carbocation?

A

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

44
Q

Which carbocation is the most stable?

A

Tertiary

45
Q

What are addition polymers?

A

Long hydrocarbon chains from from alkenes

All atoms in the original alkene are used

46
Q

How are addition polymers formed?

A

Double carbon bomb breaks,

Central carbon atoms forms two bonds to the next monomer

47
Q

Why is it difficult to dispose of polymers?

A

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

48
Q

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

A

Burning saves on landfill sites and produces energy

Some chlorinated polymers produce toxic fumes (HCl)

49
Q

How are polymers disposed using feedstock?

A

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

50
Q

Name the process used to obtain kerosene from crude oil

A

Fractional distillation

Which works because fractions have different boiling points

51
Q

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

A

Branched chains have more efficient combustion

52
Q

What is a free radical?

A

Species with an unpaired electron

53
Q

What is meant by the term fractional distillation?

A

Separation by differences in boiling point

54
Q

Why has the polymer of C2F4 very inert?

A

C-F bonds have high bond enthalpy

55
Q

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

56
Q

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

A

Chloropropanal
NaHSO4
H2O

57
Q

What are aliphatic compounds?

A

An open carbon chain - not aromatic

e.g. butane

58
Q

What are alicyclic compounds?

A

Aliphatic compounds bonded in a ring structure

e.g. cyclopentane

59
Q

What are aromatic compounds?

A

Compounds formed from a benzene ring

e.g. phenol

60
Q

What is the definition of a pi bond?

A

Sideways overlap of p orbitals

61
Q

What is the definition of a sigma bond?

A

Overlap of orbitals between atoms

Chemistry :) (17 decks)

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