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a level chemistry > B3 organics > Flashcards

B3 organics Flashcards

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1
Q

what are free radicals?

A

species with an unpaired electron.

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2
Q

what are electrophiles?

A

accepts a pair of electrons (positively charged).

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3
Q

what is a nucleophile?

A

donates a pair of electrons (lone pair).

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4
Q

what is an addition reaction?

A

2 reactants and together they form 1 product.
e.g. alkene + hydrogen > alkanes

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5
Q

what is a substitution reaction?

A

2 reactants make 2 products (swapped atoms from one reactant to another).
e.g. alkane + bromine > bromoalkane + HBr

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6
Q

what is an elimination reaction?

A

start with 1 reactant and take something out of it = 2 products (often taking away water).
e.g. ethanol > ethene + water

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7
Q

what is a redox reaction?

A

often involves a colour change.
organic oxidation = gain of oxygen and loss of hydrogen.
organic reduction = loss of oxygen and gain of hydrogen.

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8
Q

what is a hydrocarbon?

A

molecules that contain carbon and hydrogen only.

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9
Q

what is the difference between a saturated and unsaturated hydrocarbon?

A
  • saturated only single bonds.
  • unsaturated at least one double carbon bond.
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10
Q

what is a homologous series?

A

a group of compounds ends that undergo the same chemical reactions and have the same trends in physical properties and same functional groups.

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11
Q

what does aromatic mean?

A

means there is at least one benzene ring.

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12
Q

what does aliphatic mean?

A

no benzene ring.

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13
Q

what does alicylic mean?

A

subcategory of aliphatic, which is a circle of carbons that is not a benzene ring.

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14
Q

what is empirical formula?

A

lowest value of atoms within a formula.

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15
Q

what is molecular formula?

A

actual number of atoms within a formula.

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16
Q

what is displayed formula?

A

shows all bonds.

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17
Q

what is structural formula?

A

displayed formula and condensing and branches are shown in brackets.

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18
Q

what are the two types of covalent bond?

A

sigma bonds = single bonds.
pi bonds = second bond in a double or triple bond.

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19
Q

what are sigma bonds?

A

when electrons sit in orbitals (s or p orbitals) where they directly overlap the orbitals.

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20
Q

what are pi bonds?

A

pi bonds find the available space above and below the sigma bonds.
electron density spread out over a large space = weaker bond.
the sideways overlap at p orbital locks bond in place = NO rotation.

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21
Q

what is an aldehyde?

A
  • end of chain.
  • name ends in al.
  • COH.
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22
Q

what is a ketone?

A
  • middle of the chain.
  • name ends in one.
  • CO.
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23
Q

what is a carboxylic acid?

A
  • name ends in anoic acid.
  • COOH.
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24
Q

what is the ester functional group?

A
  • COO.
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25
how can you form a haloalkane from an alkane?
in presence of UV light, reacts with a halogen. free radical substitution!
26
how is an alcohol formed from a haloalkane?
heated under reflux, with NaOH(aq) etc. nucleophilic reaction!
27
how do you form an alkene from an alcohol?
heated under reflux with sulphuric acid. dehydration!
28
how do you form a haloalkane from an alkene?
reacts with hydrogen halide. electrophilic addition! // reacts with a halogen. electrophilic addition!
29
how do you form a haloalkane from an alcohol?
react with hydrogen halide heated under reflux with sulphuric acid and sodium halide. substitution reaction!
30
how do you form an alkane from an alkene?
reacts with hydrogen and nickel catalyst and 423K. added across a double bond. addition reaction!
31
how is an alcohol formed from an alkene?
reacts with steam and phosphoric acid catalyst. hydration!
32
how is a carboxylic acid formed from a primary alcohol?
heated under reflux, using excess of potassium dichromate(VI) and concentrated sulphuric acid. orange > green colour change. oxidation!
33
how is an aldehyde formed from a primary alcohol?
oxidising agent: potassium dichromate (VI) and sulphuric acid. distilled immediately! orange > green colour change. oxidation!
34
how is a ketone formed from a secondary alcohol?
heated under reflux with potassium dichromate and sulphuric acid. oxidation!
35
what is the catalyst for cracking?
aluminium oxide.
36
how can alkanes combust?
completely = products of carbon dioxide and water. incompletely = soot and carbon monoxide.
37
what are the issues with carbon dioxide and how can the problem be reduced?
greenhouse gases. burn less fossil fuels.
38
what are the issues with carbon monoxide and how can the problem be reduced?
toxic. ensure a good supply of oxygen when burning fuels.
39
what are the issues with soot and how can the problem be reduced?
blackens buildings, can cause respiratory issues, global warming. ensure a good supply of oxygen when burning fuels.
40
what are the issues with sulphuric acid and how can the problem be reduced?
acid rain. remove sulphur from fuel before burning = gases pass through a scrubber containing calcium oxide and then calcium carbonate reacts with sulphur dioxide.
41
what are the issues with NOx and how can the problem be reduced?
acid rain. use catalytic converters = catalytic converter released CO, NOx and unburned hydrocarbons from exhaust gases, turning them to carbon dioxide, water and nitrogen.
42
what are the issues with unburned hydrocarbons and how can the problem be reduced?
wastes fuel. ensure engines are well-turned and there is a good supply of oxygen.
43
what is free radical substitution?
free radical - species with an unpaired electron. substitution - one atom within compound leaves and something else takes its place.
44
how are free radicals formed?
homolytic fission.
45
what are the three steps of free radical substitution?
1) initiation = start of reaction, needs UV light. 2) propagation = main reaction. 3) termination = takes all free radicals and gets rid of them (3 steps)
46
what are three examples of bad free radical?
1) multiple substitution reactions = difficult to control, stop reaction by putting in dark. 2) don't know which carbon the substitution will take place on. 3) makes unwanted side products in termination steps.
47
what type of bonds do alkane have?
sigma
48
what type of bonds do alkene have?
pi = weak as electron density is spread out over wide distance.
49
what are the three rules of E/Z isomers?
1) both slides of double bond have to contain two different side chains. 2) we assign priority over groups on each side of double bond by atomic number. 3) looking at positions of top/bottom priority across the double bond.
50
what is a E isomers?
priority on different levels.
51
what is a Z isomer?
priority on same level.
52
what type of fission occurs in curly arrow mechanisms?
heterolytic fission = pair of electrons from covalent bond move to one atom.
53
what is markovikov's rule?
intermediate that has our positive carbocation is stable > stability occurs when the carbocation has the most 'C's around it. stable carbocation = major product.
54
how to test for unsaturation of alkenes:
reaction of alkenes and bromine can be used to identify if a C=C bond is present. when bromine water is added to alkene, bromine adds across double bond. orange > colourless colour change.
55
what are the issues of polymers?
polymers are very unreactive = non-biodegradable. polymer waste has serious environmental affects like killing aquatic life.
56
how can you reduce the environmental impact of polymers?
- recycling polymers by decreasing amount of waste going to landfill. - waste polymers are incinerated to produce heat, generating steam to drive turbine producing electricity. - feedstock recycling is the chemical and thermal processes which reclaim monomers, gases or oil from waste polymers.
57
what is PVC recycling?
disposal and recycling of PVC is hazardous due to high chlorine content. dumping PVC = not sustainable. burning PVC = releases HCl and other pollutants.
58
what are biodegradable and photodegradable polymers?
- biodegradable polymers are broken down by microorganisms into water, carbon dioxide and biological compounds. - compostable polymers degrade and leave no visible or toxic residues = based on polylatic acid. - photodegradable polymers contain bonds that are weakened by absorbing light.
59
what is a primary alcohol/haloalkane?
2 or more hydrogens on carbon next to functional group.
60
what is a secondary alcohol/haloalkane?
1 hydrogen on the carbon next to functional group.
61
what is a tertiary alcohol/haloalkane?
no hydrogen on carbon next to functional group.
62
what prefix do you use for alcohols when there is other functional groups on molecules?
hydroxy...
63
what colour flame is seen for the combustion of ethanol?
blue.
64
what does the first [O] of a primary alcohol form?
aldehyde (partial [O], we can stop at this stage by making conditions less extreme)
65
what does the secondary [O] of a primary alcohol form?
carboxylic acid (full [O])
66
what does [O] of a secondary alcohol form?
ketone > conditions less important as can't be oxidised further.
67
conditions for full [O]:
concentrated sulphuric acid. reflux reaction and distill of product.
68
conditions for partial [O]:
heat and distill immediately. 3M sulphuric acid.
69
what tests can you do to prove rate of reaction?
1) prove C-I bond is the weakest as AgI forms the fastest (disappearing cross X). 2) identify haloalkane from colour of ppt and test with ammonia.
70
what is the overall reaction when proving rate of reaction?
haloalkane + silver nitrate (aq) > alcohol + silver halide + H+ (aq) + NO₃-(aq)
71
what is the ozone layer?
O₃, which filters much of the sun's harmful UV radiation. ozone provides UV protection from UV radiation which damages DNA.
72
what is the ozone formation equation?
O₂ + uv light > O* + O* O* + O₂ > O₃
73
what are CFCs - chlorofluorocarbons?
contains Cl, C and F. they are bad for the environment.
74
what is the initiation step in CFCs and ozone?
CF₃Cl > CF₃ + Cl* uv light provides energy to break C-Cl bonds.
75
what is the propagation steps of CFCs and ozone?
O₃ + Cl* > O₂ + ClO* O₃ + ClO* > 2O₂ + Cl* Cl* radicals destroy ozone layer.
76
what is the propagation steps of NOx and ozone?
O₃ + NO > O₂ + NO₂ O* + NO₂ > O₂ + NO stratosphere produces nitrogen oxides from aircraft emissions and thunderstorms.

a level chemistry (8 decks)

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