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Edexcel Chemistry A level > Organic (1) > Flashcards

Organic (1) Flashcards

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1
Q

What type of reaction do Halogenoalkanes go through with water? What is produced?
What are the conditions and why is it a slow reaction?

A
  • Nucleophilic substitution
  • an alcohol is produced
  • Heat with water
  • Because water is a very weak nucleophile
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2
Q

What type of reaction do Halogenoalkanes go through with NaOH?
What is produced?
What are the conditions?
Describe the mechanism of reaction
What is the overall reaction?

A
  • nucleophilic substitution
  • an alcohol is produced
  • conditions: under reflux (since some compounds are volatile) and NaOH has to be warm.
  • Lone pairs from OH- ion attack delta positive on C-X bond, then jumps to delta negative X
  • OH replaces the X, forming an X ion.

OVERALL: R-X + NaOH —> NaX + R-OH

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3
Q

What type of reaction do halogenoalkanes go through with cyanide ions? (KCN)
What is produced?
What are the conditions?
Describe the mechanism
Overall reaction?

A
  • nucleophilic substitution
  • a nitrile is formed
  • warm, ethanolic, under reflux
  • lone pair on CN- attacks δ+ C, and then δ- X group. CN ion replaces X group.
  • R-X + KCN —-> R-CN + KX
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4
Q

What type of reaction do halogenoalkanes go through with Ammonia?
What is produced?
What are the conditions?
Describe the mechanism
Overall reaction?
Observations?

A
  • Nucleophilic substitution
  • Amine (identified by fishy smell)
  • EXCESS CONC AMMONIA sealed container, heated.
  • 1st NH3 attacks the C, and then the X, then 2nd NH3 acts like a base, which attacks the H, and then going to the δ+ N.
  • R-X + 2NH3 —–> R-NH2 + NH4-X
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5
Q

What is the suffix for ketones?

A

-one

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6
Q

What is the suffix for aldehydes?

A

-al

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7
Q

Define structural isomer

A

Same molecular formula, but different structural formula

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8
Q

Define chain isomers

A

Compounds with the same molecular formula, but different carbon skeleton structures (eg adding in methyl groups)

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9
Q

Define position isomers

A

Compounds with the same molecular formula but different structures due to different positions of the same functional group on the carbon skeleton.

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10
Q

define reforming

A
  • turns straight chain hydrocarbons into cyclic and aromatic hydrocarbons
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11
Q

Explain why CO is harmful to humans

A
  • CO can form a strong bond to Hemoglobin
  • Has a stronger bonding affinity than oxygen, so prevents oxygen bonding to hemoglobin.
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12
Q

What do catalytic converters do?

A
  • remove NO, CO, and other harmful gasses and turn them into less harmful gasses like NO2, CO2 and H2O.
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13
Q

Describe the structure of a catalytic converter.

A
  • honeycomb structure
  • coated with palladium, platinum and Rhodium which gives it a greater SA.
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14
Q

Explain why diff alkanes in crude oil can be seperated by fractional distillation

A
  • different length carbon chains
  • so different boiling points
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15
Q

A student researched the reaction of propane with bromine and found that the
reaction could be used to make 1-bromopropane.
(i) The first step of the reaction involves
(1)
A heterolytic bond fission to form free radicals
B heterolytic bond fission to form ions
C homolytic bond fission to form free radicals
D homolytic bond fission to form ions

A

C- homolytic bond fission to form free radicals

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16
Q

Give a possible reason why this reaction might not proceed according to the equation:

2C10H22 + 6NO —> 31N2 + 22H2O + 20CO2

A
  • NO may react with oxygen to form other oxides of nitrogen.
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17
Q

Describe two characteristics of a homologous series.

A
  • same functional group
  • same general formula
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18
Q

Explain how oxides of sulfur and oxides of nitrogen can be formed from the combustion of fossil
fuels.

A
  • some fossil fuels may contain sulfur impurities, which react with oxygen during combustion and produce sulfur oxides.
  • Nitrogen from the air may react with oxygen to produce nitrogen oxides.
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19
Q

Explain the two major reasons for cracking hydrocarbon

A
  • during cracking, a shorter chain alkane and alkene is produced.
  • shorter chain alkanes are more in demand, as they can be used as fuel.
  • they are also more useful in making things such as polymers and alcohols.
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20
Q

Explain why isomers of hexane have lower boiling temperatures
and so are found in the petrol fraction.

A
  • isomers of hexane may be branched
  • so branched chains have a lower SA
  • therefore london forces will be weaker, so takes less energy to boil them .
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21
Q

State the conditions and steps for free radical substitution reactions of alkanes.

A
  1. Initiation - UV light - free radical is made.
  2. Propagation (1) - free radical reacts with alkane, removing a H. This forms a free radical with the original alkane.
  3. Propagation (2) - alkane free radical reacts with a MOLECULE to produce the main product and another small free radical
  4. Termination: Free radical is reacted with another free radical, or another alkane molecule, or 2 molecules of alkane reacted together to stop reaction.
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22
Q

Write the propagation steps to show the formation of C2H5Cl.

A

C2H6 + Cl* —> C2H5* + HCl
C2H5* + Cl2—> C2H5Cl + Cl*

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23
Q

State how some butane, C4H10, is formed in the reaction.

A

2 C2H5 free radicals react together.

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24
Q

Describe the stages by which the Following reaction occurs in a catalytic converter.

2CO + 2NO —> N2 +CO2

A

Adsorption of gasses on the surface of catalytic converter
Weakening of bonds on catalytic surface
De-adsorption of gasses

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25
Q

Ethane can also be converted into chloroethane.
Give the reagent and conditions for this to occur

A
  • UV light
  • Chlorine
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26
Q

Describe pi bonds

A
  • exposed
  • ## have high electron density
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27
Q

Describe how sigma bonds are formed

A
  • one sp2 orbital from each carbon overlap from a single C-C bond - middle area between pi bonds.
  • so rotation can occur around a sigma bond
28
Q

Describe how Pi bonds are formed

A
  • formed by sideways overlap of 2 p orbitals from each carbon, formed above and below the plane of the molecule
  • so vulnerable to attack by other molecules, weaker than sigma bond.
29
Q

Ethene can also be converted into chloroethane.
identify the reagent for this reaction.

A
  • HCl
30
Q

Describe the mechanism of reaction of ethene being converted to chloroethane.

A
  • arrow going from double bond to H-Cl, Then electron pair moves from H-Cl BOND to Cl.
  • forms Cl- and carbocation.
  • Cl- reacts with carbocation and forms chloroethane.
31
Q

What type of reaction is alkenes reacting with Bromine/chlorine

A

electrophillic addition

32
Q

What type of reaction is an alkene reacting with H?

A

Addition

33
Q

The symbols are used to sort the plastic products into groups of specific types of plastic
when they are thrown away.
Some plastic products can be cleaned and used again.
Give two other uses of waste plastic.

A
  • re-moulded into different products
  • burned as a fuel
34
Q

Deduce a chemical test which would give a positive result for 2-Chloropropene but not for 2-chloropropane
Include the reagent and observation.

A
  • Bromine water
  • brown solution goes colourless
35
Q

Some polymers are disposed of by incineration. Ignoring any economic considerations,
explain why incineration is not a suitable method for the disposal of poly(chloroethene).

A
  • incineration may produce HCl
  • which could cause acid rain
36
Q

Chloroethene has a boiling temperature of 260 K and is known to be carcinogenic. Use
these facts to state one precaution that chemists should take when using this compound.

A

wear gas mask

37
Q

Compare and contrast how each of these monomers forms a polymer (4)

Cyclohexane
4-hydroxycyclohexanecarboxylic acid

A
  • both form from several monomer units
  • cyclohexane forms through addition polymerisation
  • second one forms from condensation polymerisation
  • no extra products formed except poly cyclohexane in cyclohexane
  • but water formed with second one.
38
Q

Butane-1,4-diol can be synthesised from but-2-ene-1,4-diol, by reaction with a reagent, B

identify B and the conditions needed for this reaction.

A
  • H2
  • nickel catalyst
39
Q

What type of reaction is the previous one?

A
  • reduction/addition
40
Q

What commercially important product can be produced by the previous reaction?

A

Margarine

41
Q

LiAlH4 is a source of hydride ions, H−
.
Give a possible reason why LiAlH4 cannot be used to reduce alkenes.

A
  • H- is a nucleophile, and alkenes cannot go through nucleophilic substitution reactions.
42
Q

Step 2 is incorrect because alcohols can only be converted to nitriles via an intermediate
compound.
Identify a suitable intermediate compound by name or formula.

A
  • 1-chlorobutane
43
Q

Give the additional reagent that should be added after heating under reflux with
aqueous sodium hydroxide, to produce
pentanoic acid.

A

HCl

44
Q

what reagant and conditions will produce ethanol from ethene

A
  • Steam
  • acid
45
Q

Explain why, 1-chloropropane and concentrated ammonia solution are heated in a sealed container

A
  • heating increases rate of reaction
  • sealed container means no gases escape
46
Q

Give a reason for the addition of ethanol to each test tube of the halogenoalkanes

A
  • to dissolve the halogenoalkanes
47
Q

The precipitates form as a result of reactions between aqueous silver ions and
aqueous halide ions.
Explain why halide ions are present in the mixture containing a halogenoalkane which
has only covalent bonds.

A
  • halogenoalkane is hydrolysed by water
  • so the C-Halogen bond breaks
48
Q

This is a question about the hydrolysis of halogenoalkanes.
Devise an experiment, giving outline details only, that would enable the relative rates of
hydrolysis of halogenoalkanes to be compared.

A
  • take 3 diff test tubes with same vol of ethanol
  • add a few drops of each halogenoalkane, the same number of drops to each test tube
  • put in water bath to keep temp the same for all of test tubes
  • put in same vol of silver nitrate in the test tubes, start stopwatch
  • see how long it take for pp to form
49
Q

This question is about esters with the molecular formula C6H12O2.
Propyl propanoate has the structure shown.
Devise a synthetic pathway to prepare propyl propanoate starting with
1-bromopropane as the only organic compound.
Include the reagents for each step in the synthesis, and the names or structures of
the intermediate compounds.

A
  1. OH- + CH2BrCH2CH3 —> CH2OHCH2CH3 (propan-1-ol)
  2. CH2OHCH2CH3 + K2Cr2O7 (H2SO4) —> CH3CH2COOH (propanoic acid)
  3. CH2OHCH2CH3 + CH3CH2COOH —> CH3CH2COCH2CH2CH3 (propyl propanoate)
    II
    O
50
Q

Describe three ways in which this apparatus must be modified for safe and efficient
use. Assume the apparatus is suitably clamped.

A
  • bulb of thermometer should be above the liquid
  • conical flask should be open
  • water in and out should be reversed
51
Q

Explain the trend in reactivity of the primary chloro-, bromo- and iodoalkanes with aqueous
hydroxide ions.

A
  • The reactivity increases down the group
  • due to the bond enthalpy of the C-Halogen
52
Q

Under different conditions, 2-chloro-2-methylpropane can react to produce 2-methylpropene.
State the reagent and conditions needed for this reaction.

A
  • KOH
  • Heat under reflux
53
Q

Explain what is meant by the term stereoisomers.

A
  • same structural formula
  • different arrangement of atoms in space
54
Q

CH3CH2CH2CH2OH reacts with the oxidising agent potassium dichromate(VI) in dilute
sulfuric acid.
Two organic products can be formed, depending on the conditions.
Write a balanced equation for the formation of one of these products, giving its name and
the condition required to achieve this product in high yield.
Use [O] in the equation to represent each oxygen atom from the oxidising agent.
(3)

A

Equation:

CH3CH2CH2CH2OH + 2[O] —> CH3CH2CH2COOH

Product name: Butanoic acid

Conditions: Heat under reflux

55
Q

Some alcohols can be oxidised by acidified sodium dichromate(VI), Na2Cr2O7.
Reflux apparatus can be used to carry out the oxidation of alcohols.
Using the apparatus for distillation instead of reflux is not an efficient way to produce
ethanoic acid from ethanol. Explain why.

A
  • distilling it will mean that ethanol is oxidised to ethanal
  • so since ethanal is more volatile, it will evaporate.
56
Q

Discuss the improvements that should be made to the set-up of the apparatus. Include the
likely effect of the errors identified on the yield or purity of the product.
Assume the apparatus is suitably clamped.

A
  • Add more ice water mixture
  • to collect as much product as possible
  • the thermometer should not be touching the liquid - supposed to be measuring the gases’ temperature
  • add anti bumping granules
  • to prevent any large bubbles from forming
57
Q

*A sample of flavan-3-ol extracted from wine contained some ethanol. The sample
was left in a flask, open to the air for several days. The contents were then analysed
to identify any new compounds formed. Several new compounds were found to be
present, including some with a distinctive fruity smell.
Identify four new organic compounds that could form under these conditions
by considering the chemistry of alcohols. Justify your answers. Include the
structure of two compounds formed from flavan-3-ol, one of which has a fruity smell.

A
  • flavan-3-ol could have been oxidised by oxygen in the air
  • first it could’ve been oxidised to ethanoic acid
  • Ethyl ethanoate then formed from ethanol and ethanoic acid reacting together
58
Q

The steps for the preparation of impure 1-bromobutane are summarised.
Step 1 Dissolve the sodium bromide in distilled water in a pear-shaped flask and then
add 20.0 cm3 of butan-1-ol.
Step 2 Surround the flask with an ice bath to cool the mixture, before adding
concentrated sulfuric acid drop by drop.
Step 3 Remove the flask from the ice bath and add a few anti-bumping granules to the
reaction mixture.
Step 4 Set up the apparatus for heating under reflux. Heat the mixture in the flask for 30
minutes and then allow the apparatus to cool.
Step 5 Rearrange the apparatus for distillation and heat the mixture until no more
1-bromobutane distils over.
(i) Parts of the method are given in bold type in Steps 2, 3 and 4.
Give a reason why each of these parts is necessary.

A
  • heat under reflux to prevent loss of any volatile compounds
  • anti bumping granules to prevent large bubbles from forming
  • ice bath to cool down the mixture since it releases a lot of heat.
59
Q

State how the granules prevent bumping.

A
  • provides a surface for smaller bubbles to form
60
Q

give a reason why petrol should not contain heptane

A
  • does not burn efficinetly
61
Q

What conditions are required for thermal cracking? Temp, pressure?

A

1000 degress celcius
60-70 atm

62
Q

What conditions are required for Catalytic cracking? temp, pressure, catalyst?

A
  • 350 degrees celcius
  • zeolite catalyst.
  • slight pressure
63
Q

Why are aromatic and cyclohydrocarbons useful for? Why?

A
  • useful as fuels in motor vehicles
  • due to less knocking as compared to straight chain hydrocarbons in engines.
64
Q

What are the conditions for reforming?

A
  • ## platinum catalyst
65
Q

What are the conditions required to go from alkene—-> ethanol name the reagent and conditions.

A
  • STEAM
  • 300 degrees C
  • 60 atm
    Phosphoric acid catalyst
66
Q

What are the reagent and conditions to go from alcohol —> alkene
Name any observations seen.

A
  • acidified potassium Manganate
  • solution turns from purple to colourless.

Edexcel Chemistry A level (18 decks)

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