Organic Flashcards

1
Q

Organic Chemistry

A

Study of the compounds of carbon

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2
Q

Hydrocarbon

A

A compound that only contains carbon and hydrogen

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3
Q

Fossil fuels

A

Fuels that were formed from the remains of plants and animals that lived millions of years ago

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4
Q

Saturated compound

A

There are only single bonds between the atoms in the molecule (Alkanes)

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5
Q

Homologous series

A

A series of compounds of similar chemical properties, showing gradations (successive changes) in physical properties , and having a general formula for its members. Each member has a similar method of preparation, and each memeber differs from the previous member by a CH2 unit

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6
Q

Structural isomers

A

Compound with the SAME MOLECULAR formula but different structural formulas (e.g 3 isomers of pentane)

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7
Q

Unsaturated compound

A

A compound that contains 1+ or more double/triple bonds between the atoms in the molecule (e.g. Alkenes)

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8
Q

Aliphatic compound

A

An organic compound that consists of open chains of carbon atoms and closed chain compounds(rings) that resemble them in chemical properties

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9
Q

Aromatic compounds

A

Compounds that contain a benzene ring structure in their molecules

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10
Q

What about benzene (discovered by Michael Faraday) puzzled chemists?

A
  1. Reactivity (predicted- highly reactive, actually not)

2. Bond lengths (all the c-c bond lengths are the same, single usually longer)

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11
Q

Auto-ignition

A

Early ignition of the petrol-air mixture before normal ignition of the mixture by a spark

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12
Q

Octane number

A

The measure of the tendency of the fuel to resist knocking

e.g. 2,2,4-trimethylpentane used because it has a low tendency, and an octane no. of 100

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13
Q

Catalytic cracking

A

The breaking down of long—chain hydrocarbon molecules into short-chain molecules by the action of heat & catalysts

(Greater demand for shorter, higher octane no. & more branched)

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14
Q

Benefit of catalytic cracking?

A

Alkenes produced are used to manufacture various materials, e.g. ethene—>polyethene—>making plastic bags

Important for the petrochemicals industry

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15
Q

Heat of reaction

A

The heat change when the numbers of moles of reactants indicated in the balanced eqn. for the reaction react completely

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16
Q

Heat of combustion

A

The heat change when one mole of a substance is completely burned in excess Oxygen.

Measured using a bomb calorimeter

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17
Q

Calorimeter

A

Any container used for the determination of heat changes (e.g. bomb calorimeter- measuring heat if combustion)

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18
Q

Kilogram calorific value

A

The heat energy produced when 1kg of the fuel is completely burned in oxygen

Use- helps us to compare the efficiency of various fuels

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19
Q

Name a fuel with a high kilogram calorific value

A

Methane- an excellent fuel

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20
Q

What happens when a chemical reaction occurs?

A

Bonds are broken & new bonds are formed

-Energy required to break bonds & energy released when they’re formed

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21
Q

Bond energy

A

The average energy required to break one mole of a particular covalent bond and to separate the neutral atoms completely from each other

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22
Q

Why are bond energy values an average of energy?

A

Bond energy for a particular bond can vary

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23
Q

Neutralisation

A

The reaction between an acid and a base to form salt and water

-e.g. Acid(HCL)+base(NaOH)=NaCl+ H2O

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24
Q

Heat of neutralisation

A

The heat change when one mole of H+ ions from an acid reacts with one mole of OH- ions from a base

-measured in kJmol-1

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25
Q

Heat of formation

A

The heat change that takes place when one mole of a compound in its standard state is formed from its elements in their standard state

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26
Q

Hess’s Law

A

If a chemical reaction takes place in a number of stages, the SUM of the HEAT CHANGES in the separate stages is equal to the heat change if the reaction is carried out in one stage

(Amount of heat absorbed in a chemical reaction is the same no matter how many steps it takes place in)

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27
Q

Why is Hess’s Law so useful?

A

Allows thermochemical eqns. to be added, subtracted, multiplied, or divided to find the unknown heats of reaction.

(Useful in thermochemistry)

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28
Q

The Law of Conservation of Energy

A

Energy can’t be created or destroyed, it can only be converted from one form of energy to another

One form of energy—> another

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29
Q

Functional group

A

An atom/group of atoms that’s responsible for the characteristic properties of an organic compound/series of organic compounds

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30
Q

Primary alcohol

A

Where the Carbon atom joined to the -OH group is attached to only one other Carbon atom

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31
Q

Secondary alcohol

A

When the Carbon atom joined to the -OH group is joined to 2 other Carbon atoms

(E.g. Ethanol)

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32
Q

Tertiary alcohol

A

When the Carbon atom joined to the-OH group is attached to 3 other Carbon atoms

33
Q

Condensation reaction

A

A chemical reaction where 2 molecules combine to form a bigger molecule with the loss of a smaller molecule such as water

34
Q

Emulsion

A

A dispersion of small droplets of one liquid in another liquid in which its not soluble

35
Q

Substitution reaction

A

A chemical reaction where an atom or group of atoms in a molecule is replaced by another atom/group of atoms

36
Q

Mechanism

A

The detailed step-by-step description of how the overall reaction occurs

37
Q

Chain reaction

A

A reaction that continues on and on because a product from one step is a reactant for another step of the reaction

38
Q

How is soap made?

A

Saponification

39
Q

Addition reaction

A

2+ molecules react together to form a single molecule

Polarisation
Heterolytic Fission
Carbonise Ion Formation
Ionic Addition

40
Q

Polymers

A

Long chain molecules made by joining many small molecules

41
Q

Repeating unit of a polymer

A

The part of the polymer whose repetition produces the complete polymer chain (except for the end groups)

42
Q

Elimination reaction

A

A small molecule is removed from a larger molecule to leave a double bond in the larger molecule

43
Q

E.g. of an oxidation reaction

A

Conversation of a primary alcohol—>aldehyde

2 hydrogen atoms removed from primary alcohol

44
Q

Organic Synthesis

A

The process of making organic compounds from simpler starting materials

45
Q

Recrystallisation

A

A process of repeated crystallisation to purify a solid/to obtain more satisfactory pure crystals

46
Q

Chromatography

A

A separation technique where a mobile phase carrying a mixture moves into contact with a selectively absorb any stationary phase

47
Q

Principle of chromatography

A

Separation of a mixture of components occurs as a result of selective ADSORBANCE of the components on a stationary kosher while carried by a mobile phase

48
Q

Principle of gas chromatography

A

A gaseous mobile phase is in contact with a stationary phase & separation of the mixture occurs as a result of SELECTIVE ADSORBANCE of the components of the mixture on the stationary phase

49
Q

E.g. of a weak oxidising agent

A

Fehling’s reagent

50
Q

Product of the reaction of Hydrogen chloride + Ethene?

A

Addition reaction—> chloroethane

51
Q

Explain infrared spectrometry

A

Infrared radiation is absorbed by vibrations of the bonds in the molecules of organic compounds

52
Q

Conversion of Ethane—Chloroethane

A

Substitution reaction

53
Q

A test for saturation?

A

Add bromine to each sample

Saturated—>colourless
Unsaturated—>stays brown

54
Q

Purpose of dehydrocyclisation

A

Increases octane number to resist knocking

55
Q

Methods of manufacturing Hydrogen gas on a large scale?

A

Electrolysis of water (expensive)

Steam reforming of natural gas

56
Q

Important use of Hydrogen?

-environmentally friendly

A

Production of Ammonia (NH3)

Production of margarine (low fat)

57
Q

Chloroalkane

A

A compound where 1+ of the Hydrogen atoms in an Allan Coe molecule have been replaced by Chlorine

58
Q

Refinery gas use

A

LPG for cooking (Liquified Petroleum Gas)

59
Q

Mercaptans?

A

(Sulfur compounds)

Added to odourless gases to give them a smell so leaks can be detected

60
Q

Why is methane a great fuel?

A

High energy output

Burns cleanly

61
Q

What is the efficiency of a fuel measured by?

A

Th fuels low tendency to auto-ignite

Higher the octane no.- more efficient

62
Q

Most efficient fuel?

A

2,2,4-trimethylpentane (crane no. Of 100) )

Efficiency:

  • Branched
  • short chain
63
Q

Least efficient fuel?

A

Heptane (octane no. Of 0)

-straight chain

64
Q

What is the early ignition/explosion caused by?

A

The petrol-air mixture

65
Q

3 factors that effect octane numbers

A

Chain length—> shorter- higher octane no.
Branching/side groups—> more branched- higher octane no.
Cyclic compounds—> higher octane no.

66
Q

E.g. of a cyclic compound with a high octane no.?

A

Cyclohexane—>higher than hexane

67
Q

Ways to increase the octane no. of a fuel/petrol?

A

Isomerisation
Dehydrocyclisation
Catalytic cracking
Adding oxygenates

68
Q

Why isn’t lead used anymore to reduce knocking in cars?

A

Lead is toxic

Poisons the catalyst in the catalytic converter

69
Q

Residue of fractional distillation (Bitumen) use

A

For roads/roofs

70
Q

Kerosene use

A

Central heating/aircraft fuel

71
Q

Naphtha use

A

Making petrol/ chemicals

71
Q

Isomerisation

A

Changing long chain hydrocarbons into shorter more branched chains to increase the octane no.

E.g. pentane—>2-methylbutane

71
Q

Catalytic cracking

A

Breaking down long chain hydrocarbons into shorter chain hydrocarbons to increase octane no. (For fuel+plastics)

71
Q

Dehydrocyclisation

A

Catalysts used to form cyclic compounds
Involves removal of hydrogen
Alkanes—>cycloalkanes

71
Q

Purpose of adding oxygenates?

A

Oxygenate is a fuel that contains Oxygen, added to a fuel to increase its octane no. & gives rise to little pollution

E.g. methanol/ethanol/MTBE

71
Q

E.g. of oxygenates added to fuel to increase octane no.? +advantages

A

Ethanol/methanol/MTBE

Give rise to little pollution

71
Q

Burning hydrogen as a fuel?

A

Product: water as hydrogen mixes with O in air
Environmentally friendly
Problem: forms an explosive mixture with air (problems with storage)

72
Q

Organic compound with a fruity smell?

A

Esters