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Organic Chemistry Flashcards

1
Q

Crude oil

A

Remains of ancient biomass consisting mainly of plankton

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2
Q

Hydrocarbons

A

Molecules made up of carbon and hydrogen only

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3
Q

About alkanes

A
  • CnH2n+2
  • MEPB (methane, ethane…)
  • saturated hydrocarbons (molecules with only single bonds between C atoms)
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4
Q

Fractional distillation

A

Evaporation:

  • Crude oil is heated until it evaporates.
  • Crude oil vapour is put into a fractionating column at the bottom and rises upwards

Condensation:

  • The temperature is highest at the bottom of the column. Long-chain hydrocarbons condense at the bottom and are collected as liquids.
  • Short-chain hydrocarbons have lower boiling points -> they pass up the column and condense at lower temperatures nearer the top
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5
Q

Petrochemicals

A

The fractions in fractional distillation can be processed to produce fuel and feedstock for the petrochemical industry
-> eg kerosene

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6
Q

Properties of hydrocarbons

A
  • the shorter the molecules the less viscous
  • the shorter the lower its boiling point
  • the shorter the more flammable
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7
Q

The 2 cracking processes of hydrocarbons

A
  1. Passing them over a hot catalyst (catalytic cracking)
  2. Mixing them with steam and heating to very high temperatures -> so that thermal decomposition can occur (steam cracking)
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8
Q

Alkenes

A
  • CnH2n
  • unsaturated (have at least one carbon double bond)
  • first 4 are ethene, propane, butene and pentene
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9
Q

Test for alkenes

A

React with bromine water to turn it from orange to colourless

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10
Q

Why don’t alkanes react with bromine water

A

Because it doesn’t have a double bond like alkene which makes alkenes more reactive

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11
Q

Why are products of cracking useful as fuels

A

They have shorter chains than the original alkanes making them more flammable

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12
Q

Alkenes reactions

A

With oxygen:
- burn in air with smoky flames because of incomplete combustion (C or CO is formed)

also react with halogens, water and hydrogen
- the double bond breaks and joins with the new reactant

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13
Q

Alkenes with halogens, water and hydrogen (hydration, hydrogenation, halogenation)

A
  • the C=C breaks to form a C-C bond
  • the added compounds splits in 2 and are added to either of the Cs
  • H2O splits into H and OH, H2 splits into 2 Hs and Br2 splits into 2 Brs
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14
Q

What is the alcohol functional group

A

-OH

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15
Q

The first 4 alcohols and their letter symbols

A

Methanol -> CH3OH
Ethanol -> C2H5OH
Propanol -> C3H7OH
Butanol -> C4H9OH

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16
Q

Reactions of alcohols

A

ignite ethanol:
- burn to produce carbon dioxide and water
- burns easily with blue flame

add water to universal indicator:
- dissolve to form a neutral solution (pH 7)

with sodium:
- bubbles/fizzing
- to produce hydrogen and a salt

warm with acidified sodium dichromate solution:
- sodium dichromate turns orange from green

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17
Q

Uses of alcohols

A
  • methanol: chemical feedstock
  • ethanol: alcoholic drinks
  • fuel
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18
Q

Hydrogenation

A

Alkene + hydrogen → alkane

-> needs a catalyst

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19
Q

Hydration

A

Alkene + water (steam) → alcohol

-> needs hot temperatures and a catalyst

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20
Q

Halogenation

A

Alkene + halogen → halogenoalkane

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21
Q

2 ways of preparing ethanol

A
  1. Fermentation
  2. Hydration of ethene with steam
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22
Q

What is the functional group of carboxylic acids

A

-COOH

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23
Q

Letter symbols for the first few carboxylic acids

A

Methanoic acid -> CHOOH
Ethanoic acid -> CH3COOH
Propanoic acid -> C2H5COOH
Butanoic acid -> C3H7COOH

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24
Q

Reactions of carboxylic acids

A

with water:
- dissolve in water to produce acidic solutions

with metal carbonates:
- produce carbon dioxide, water, salt

with alcohols:
- to produce esters (needs an acid catalyst)

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25
What does ethanol and ethanoic acid make
Ethyl ethanoate
26
Esters
- don’t completely ionise in solutions, so don’t release many H+ ions , making carboxylic acids weak acids -> this means they have a higher pH than solutions if strong acids of the same concentration
27
Addition polymers
- formed by the joining up of many monomers to form polymers - only occurs in monomers that contain C=C bonds (alkenes)
28
Condensation polymers
formed when monomers with 2 different functional are joined together -> when they join they usually lose small molecules like water
29
Pollsters
formed from two different monomers and produce water
30
Amino acids
- have 2 different functional groups in a molecule (an amine group and a carboxylic acid group) - they react by condensation polymerisations to produce polypeptides - different amino acids can be combined in a chain to form proteins
31
DNA
- two polymer chains made up of monomers called nucleotides in a double helix
32
Other naturally occurring monomers
Protein -> amino acids Starch -> glucose Cellulose -> glucose
33
What happens to volume of gas when temperature increases
It also increases
34
What happens to volume of gas when pressure increases
It decreases
35
Uses of ethanol
- solvent (cosmetics, paints, alcoholic drinks) - disinfectants - fuels
36
Advantages and disadvantages of fermentation
Adv - takes places at lower temp -> lower energy cost - raw materials -> sugar is renewable Disadv - CO2 is a waster product -> low atom economy - slow reaction - yield is low - batch process - ethanol is impure
37
Advantages and disadvantages of hydration of ethene with steam to make ethanol
Adv - fast reaction - high yield - 100% atom economy - ethanol is pure - continuous process Disadv - energy cost is high - need high temp and pressure - safety -> high pressure - ethene -> crude oil is non-renewable
38
What are biofuels made from
Biological sources Eg, ethanol use as fuel
39
Alcohol general formula
CnH2n+1OH
40
Reactions of carboxylic acids
**with carbonates:** - gentle fizzing **with alcohol:** - makes esters
41
Name the one ester we have to know
Ethyl ethanoate
42
Uses of esters
- perfumes/nice fragrances - plasticisers - artificial flavourings
43
What is a polymer
Long chain molecule made up of lots of repeating units (monomers) linked together
44
Addition polymers
- the monomers are alkenes - made up of all the same monomers - only one product - always synthetic - non-biodegradable
45
Condensation polymers
- the monomers contain different functional groups - not alkenes - two products -> polymer + water - can be synthetic - biodegradable
46
What is a polyester formed from
Dicarboxylic acid and a diol
47
What are polyamides formed from
Dicarboxylic acids and diamine
48
What is a polypeptide
Chain of amino acids
49
What are starch and cellulose
Natural condensation polymers of glucose
50
Thermosetting polymers
- high melting points and durable - as polymer chains are held together by cross-links (covalent bonds)
51
Thermosoftening polymers
- low melting points and soft on heating - as they only have weak intermolecular forces between polymer chains
52
What is addition polymerisation
Where alkene monomers link together to produce one saturated product (alkane)
53
Combustion of hydrocarbons
Releases energy -> during combustion the carbon and hydrogen in the fuels are oxidised -> complete combustion of a hydrocarbon produces carbon dioxide and water
54
Products of cracking
Alkanes and alkenes
55
Why are products of cracking useful
There is a high demand for fuels with small molecules
56
Functional group of alkenes
C=C
57
Combustion of alkenes
Alkenes react with oxygen in combustion reactions and tend to burn in air with smoky flames because of incomplete combustion
58
First 4 alcohols
Methanol Ethanol Propanol Butanol
59
Why are carboxylic acids weak acids
they only partially ionise in water, releasing only some of their hydrogen ions and so pH increases
60
First 4 carboxylic acids
Methanoic acid Ethanoic acid Propanoic acid Butanoic acid
61
What is used to make polymers
Alkenes
62
Amino acids
- Have 2 different functional groups - react by condensation polymerisation to produce polypeptides
63
DNA
two polymer chains made from monomers called nucleotides in the form of a double helix
64
Naturally occurring polymers
Protein, cellulose and starch

chem (12 decks)

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