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IGCSE Chemistry (me) > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

1
Q

What is a hydrocarbon?

A

Compound that only contains hydrogen and carbon

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2
Q

Empirical formulae of H2O2

A

HO

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3
Q

Molecular formulae

A

shows the actual number of atoms in the molecule

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4
Q

Molecular formula of butane

A

C4H10

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5
Q

Chemical formula for butene

A

C4H8 (it has a double bond) meaning it is an unsaturated hydrocarbon

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6
Q

General formula of Alkane

A

CnH2n+2

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7
Q

Homologous Series

A

Members of this have the same general formula, similar chemical properties and same functional group

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8
Q

Isomers

A

Compounds that have the same chemical formulae but different molecular formulae

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9
Q

Substitution reaction

A

When one functional group replaces another e.g Methane reacts with bromine under the presence of ultraviolet

methane + bromine -> bromomethane + hydrogen bromide

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10
Q

Addition reaction

A

when two or more molecules combine to form a larger molecule

ethene + bromine -> dibromoethane

C2H4 + Br2 -> C2H4Br2

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11
Q

Combustion reaction

A

when an organic substance reacts with oxygen to form carbon dioxide and water

e.g CH4 + 2O2 -> CO2 +2H2O

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12
Q

Process of fractional distillation of crude oil

A
  • The crude oil is heated and vapourises
  • the vapour enters the fractionating column where it is hotter at the bottom and colder at the top
  • Vapours with high boiling points condense at the bottom of the column
  • Vapours with lower boiling points rise up the column and condense at the top
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13
Q

Viscosity (property of a crude oil)

A
  • Ease of flow of a liquid
  • High viscosity liquids are thick and flow less easily
  • Increasing molecular mass makes the liquid flow less easily
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14
Q

Colour (crude oil)

A

Gets darker as the carbon chain length become longer

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15
Q

Melting/boiling point of crude oil

A

when molecules get larger, the intermolecular attraction becomes greater therefore requires a lot of energy to overcome

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16
Q

Volatility (crude oil)

A

Volatility refers to the tendency of a substance to vaporise

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17
Q

Uses of Crude oil fractions

A

Liquified petroleum gas - Domestic heating & cooking

Petrol - Fuel for cars (gasoline)

Kerosene - Jet fuel (paraffin)

Diesel - Diesel engines (gas oil)

Heavy fuel oil - Ships & power stations

Bitumen - Surfacing roads and roofs

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18
Q

Combustion of fossil fuels

A

If there’s an insufficient amount of oxygen it releases carbon monoxide which binds to haemoglobin which means oxygen cannot be carried around the body

19
Q

Nitrogen Oxides

A

Nitrogen and Oxygen react to form high temp and pressure conditions for blast furnaces and combustion engines

20
Q

Sulfur dioxide

A

Fossil fuels get contaminated with small amount of sulfur impurities and get oxidised to form sulfur dioxide

Causes:
- Acid rain (corrosion)
- Pollutes crops and water supplies

21
Q

How is Acid rain formed?

A

From sulfur dioxide:
Sulfur dioxide from the fossil fuels dissolve in rain water to form sulfuric acid

From nitrogen dioxide:
It’s produced from car engines and reacts with rain water to form a mixutre of nitrous and nitric acids

22
Q

Cracking

A

Industrial process to break low demand, long chain hydrocarbons to small chain hydrocarbon molecules

23
Q

Conditions for catalytic cracking

A
  • Heat the hydrocarbon molecules at around 600-700 C to vaporise them
  • Vapours then pass over a aluminium oxide (catalyst)
  • this breaks covalent bonds since they become contact with the catalyst causing thermal decomposition reactions
24
Q

Products of cracking

A

Alkanes and Alkenes

Alkanes are saturated molecules that contain carbon-carbon single bonds

Alkenes are unsaturated molecules containing carbon=carbon double bonds

25
Q

Alkanes

A

Saturated hydrocarbons
Usually unreactive compounds but undergo combusition

26
Q

Alkanes general formula

27
Q

Halogens and Alkanes

A

In a substitution reaction, one atom swaps with another atom.

Halogens react with alkanes under the presence of ultraviolet

e.g methane + bromine -> bromomethane + hydrogen bromide

CH4 +Br2 -> CH3Br + HBr

28
Q

Alkenes

A
  • Unsaturated hydrocarbons
  • Carbon=Carbon double bond
29
Q

Alkenes general formula

30
Q

Bromine and alkenes

A

It’s an addition reaction and it makes dibromoalkane

31
Q

Test for alkenes

A

Bromine water (orange) test

  • It helps test which solution is an alkane or an alkene
  • When bromine is added to alkane the colour stays the same (orange) whereas when it is added to alkene, it becomes colourless

This is because it adds to the C=C bond causing the solution to no longer contain free bromine

32
Q

Alcohols

A
  • OH functional group
33
Q

Oxidation of ethanol

A
  • Combustion
  • Aerobic oxidation
  • Treatment with an oxidising agent
34
Q

Combustion of Ethanol

A
  • Use a spirit burner and burn the alcohol in the presence of oxygen

It forms carbon dioxide + water
2CO2 + 3H2O

35
Q

Aerobic Oxidation of Ethanol

A

Bacteria in the air use oxygen to oxidise Ethanol in wine

Ethanol + oxygen -> Ethanoic acid + water

36
Q

Treatment with an oxidising agent of Ethanol

A

Ethanol gets heated with Potassium dichromate (VI) solution in sulfuric acid, the ethanol oxidises to ethanoic acid

37
Q

Manufacturing Ethanol (2 ways)

A

Hydration of ethene:
- Temperature of around 300C
- Pressure of 60-70 atm
- Concentrated phosphoric acid catalyst
Ethene + steam -> Ethanol

Fermentation: it is where sugar or starch is dissolved in water and yeast is added
- Fermented between 25 and 35C where 30C is the optimum temperature.
- Without the absence of oxygen
- If the temperature is too high the enzymes will denature

38
Q

Carboxylic acid

A

Functional group - COOH
Methanoic acid- HCOOH
Ethanoic acid- CH3COOH
Propanoic acid- CH3CH2COOH
Butanoic acid-CH3CH2CH2COOH

38
Q

Reactions of carboxylic acids

A

They react with:
- Metals to form a salt and hydrogen
- carbonates to form a salt, water and carbon dioxide gas

39
Q

Esters

A

Alcohols and carboxylic acids react to make esters

Functional group R-OCO-R
e.g
Ethanoic acid + ethanol in the presence of concentrated sulfuric acid to form (ethyl ethanoate)

40
Q

Preparation of Ethyl ethanoate

A

Method:
1. Mix ethanoic acid, ethanol, and concentrated sulfuric acid, in a water bath
2. The ester is then distilled off as soon as it is formed by condensation
3. Esters have low boiling points therefore are first to evaporate from the reaction. Removing them from the mixture by distillation prevents the reverse reaction from occuring

41
Q

Additional polymers

A

Monomer to polymers
e.g Ethene -> Poly(ethene)

42
Q

Disposal of polymers

A

It takes up valuable land since additional polymers are non-biodegradeble.

When they get burnt it releases CO2

43
Q

Condensation polymers

A

They form the polymer and one water molecule per linkage

IGCSE Chemistry (me) (3 decks)

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