Alkanes Flashcards

1
Q

What is an empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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2
Q

What is a molecular formula?

A

The formula that shows the actual number of atoms of each element in a molecule

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3
Q

What is a general formula?

A

A generalised formula which enables you to work out the molecular formula of a compound within a homologous series

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4
Q

What is a structural or shorthand formula?

A

A formula showing the arrangement of atoms in a substance without showing the bonds. E.g. CH₃CH₂CH₃

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5
Q

What is a displayed formula?

A

A formula showing the arrangement of atoms in a substance and all the bonds E.g.

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6
Q

What is a skeletal formula?

A

A simplified version of a displayed formula where straight lines represent carbon-carbon bonds e.g.

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7
Q

What is a hydrocarbon?

A

A compound made of atoms of hydrogen and carbon only

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8
Q

What is an alkane?

A

A hydrocarbon with only single bonds.

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9
Q

What is chemical nomenclature?

A

The process of naming different organic compounds

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10
Q

Name a given branched alkane

A

Assign parent chain, assign branches a number and add as prefixes

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11
Q

What is isomerism?

A

When molecules have the same atoms but they are arranged differently in space

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12
Q

What is structural isomerism?

A

Where isomers have the same molecular formula but a different structure

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13
Q

What are the three types of structural isomerism?

A

Chain, position and functional

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14
Q

What is a saturated hydrocarbon?

A

A hydrocarbon with only single bonds

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15
Q

What is crude oil?

A

A mixture of mainly alkanes that can be separated by fractional distillation

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16
Q

What is fractional distillation?

A

The process of separating the alkanes in crude oil by use of their different melting points

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17
Q

What is cracking?

A

The process of breaking C-C bonds in alkanes to make shorter molecules

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18
Q

What are the two types of cracking?

A

Thermal cracking and catalytic cracking

19
Q

How is thermal cracking carried out?

A

At high pressure and temperature

20
Q

What is thermal cracking used for?

A

Producing a high percentage of alkenes

21
Q

How is catalytic cracking carried out?

A

Slight pressure, high temperature, zeolite catalyst

22
Q

What is catalytic cracking used for?

A

Production of motor fuels and aromatic hydrocarbons

23
Q

Why is cracking carried out?

A

The products of cracking are in greater demand than the long chain alkanes

24
Q

What is combustion?

A

The exothermic reaction of a fuel with oxygen

25
Q

What is complete combustion?

A

A combustion reaction where there is enough oxygen to ensure products are purely carbon dioxide and water

26
Q

What is incomplete combustion?

A

A combustion reaction where the lack of oxygen results in products other than carbon dioxide and water

27
Q

What can the products of incomplete combustion be?

A

Carbon monoxide, carbon

28
Q

Which pollutants are produced by the internal combustion engine?

A

Nitrogen oxides, carbon monoxide, carbon, unburned hydrocarbons

29
Q

What is the purpose of a catalytic convertor?

A

To remove gaseous pollutants produced by internal combustion engines

30
Q

How is sulphur dioxide released from combustion engines?

A

Through the combustion of hydrocarbons containing sulphur impurities

31
Q

What is a flue gas?

A

The gas released from large industrial plants and power plants

32
Q

How can sulphur dioxide be removed from flue gases?

A

By using calcium oxide or calcium carbonate to neutralise it

33
Q

What is a free radical?

A

A reactive species containing an unpaired electron

34
Q

How are free radicals signaled?

A

By use of a ∙ e.g.. Cl∙

35
Q

How are chlorine free radicals produced?

A

Exposure to UV light

36
Q

What is free radical substitution?

A

Where an atom bonded to a carbon is substituted for a free radical atom

37
Q

Which steps are involved in a free radical substitution?

A

Initiation, propagation, termination

38
Q

What is an initiation step?

A

The generation of a free radical

39
Q

Give an example of an initiation step

A

Cl₂ → 2Cl∙

40
Q

What is a propagation?

A

Intermediate steps in a free radical reaction which cause the regeneration of the original free radical

41
Q

Give an example of a propagation

A

CH₄ + Cl∙ → CH₃∙ + HCl, CH₃∙ + Cl₂ → CH₃Cl + Cl∙

42
Q

What is a termination?

A

A reaction involving two free radicals and resulting in no free radicals

43
Q

Give an example of a termination

A

CH₃∙ + Cl∙ → CH₃Cl

44
Q

Why do free radical substitutions result in impure products

A

Because there are many possible side reactions e.g. further substitution with chlorine or alkyl radical-radical reactions