Organic Chemistry Flashcards

1
Q

What is a hydrocarbon?

A

Any compound that is formed from carbon and hydrogen atoms only

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2
Q

Alkanes

A

The simplest type of hydrocarbon
CnH2n+2
Each carbon atom forms four single covalent bonds
First four alkanes are methane, ethane, propane and butane

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3
Q

Methane formula

A
CH4
     H
      |
H-C-H
      |
     H
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4
Q

Ethane formula

A
C2H6     
     H   H
      |    |
H-C-C-H
      |    |
     H   H
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5
Q

Propane formula

A

C3H8

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6
Q

Butane formula

A

C4H10

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7
Q

What gives hydrocarbon molecules varying properties?

A

They vary in size

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8
Q

What happens to the properties of hydrocarbons as the molecules get larger?

A

It gets more viscous, its boiling point gets higher, the less volatile it is, the less easily it ignites

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9
Q

Complete combustion of hydrocarbons equation

A

Hydrocarbon + oxygen —> carbon dioxide + water (+energy)

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10
Q

Why are hydrocarbons used as fuels?

A

They release a large amount of energy when they combust completely

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11
Q

Hydrocarbon combustion waste products

A

CO2 and H2O

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12
Q

How is crude oil formed?

A

Over millions of years from the fossilised remains of plankton

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13
Q

Where is crude oil found?

A

In the porous rocks in the Earth’s crust

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14
Q

What is crude oil made up from?

A

Hydrocarbons

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15
Q

How are the components of crude oil separated?

A

Fractional distillation

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16
Q

Why does fractional distillation work for hydrocarbons?

A

Different sized molecules of hydrocarbons have different boiling points

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17
Q

What piece of equipment does fractional distillation take place in?

A

Fractionating column

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18
Q

What are the stages of fractional distillation?

A

1) the crude oil is heated until it evaporates
2) the molecules move up the fractionating column which is hotter at the bottom
3) larger molecules condense at the hotter bottom of the column and are collected
4) the shorter molecules condense at the cooler top of the column and are collected

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19
Q

Cracking

A

Splitting up long chain hydrocarbons into shorter chain hydrocarbons

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20
Q

Which hydrocarbons are more useful: long chain or short chain?

A

Short chain as they are flammable so make good fuels.

Long ones for, thick gloopy liquids like tar which aren’t that useful

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21
Q

What is the process of catalytic cracking?

A

1) the hydrocarbons are heated until they vaporise
2) the vapour is passed over a hot catalyst
3) thermal decomposition then takes place

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22
Q

What are the products of cracking?

A

Both alkanes and alkenes

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23
Q

Why are hydrocarbons split into smaller molecules?

A

There is a higher demand for short hydrocarbons as they easy to ignite and have low boiling points so are used in fuels

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24
Q

What is the main difference between alkenes and alkanes?

A

Alkenes have a double carbon bond

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25
Q

What are hydrocarbons that have double bonds described as?

A

Unsaturated

Alkenes have 2 fewer hydrogens compared with alkanes containing the same number of carbon atoms

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26
Q

What is the general formula for an alkene?

A

CnH2n

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27
Q

Why are alkenes more reactive than alkanes?

A

Because of the C=C bond

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28
Q

Why do alkenes burn with a smokier flame than alkanes?

A

They go through incomplete combustion

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29
Q

What happens in incomplete combustion?

A

Carbon monoxide is produced which is poisonous. Soot is given off

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30
Q

What happens during the combustion of hydrocarbons?

A

Carbon and hydrogen are oxidised, energy is released, waste products are released into the atmosphere

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31
Q

What two types of cracking are there?

A

Catalytic cracking

Steam cracking

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32
Q

What is the method of steam cracking?

A

1) vaporise the hydrocarbons
2) mix them with steam
3) heat them to a very high temperature

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33
Q

Balanced chemical equations for cracking etc.

Decane

A

HHHHHHHHHH HHHHHHHH H H
HCCCCCCCCCCH —> HCCCCCCCCH + C=C
HHHHHHHHHH HHHHHHHH H H
decane octane Ethene(alkene)

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34
Q

Cracking equation

A

Long chain hydrocarbon —> shorter alkane molecule + alkene

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35
Q

Ethene formula

A

C2H4
H H
C=C
H H

36
Q

Propane formula

A

C3H6
H H H
H-C-C=C
H H

37
Q

Butene formula

A

C4H8
H H H H
H-C-C-C=C
H H H

38
Q

Pentene formula

A

C5H10
H H H H H
H-C-C-C-C=C
H H H H

39
Q

Standard equation for incomplete combustion of alkenes

A

Alkene + oxygen —> carbon + carbon monoxide + carbon dioxide + water

40
Q

What does incomplete combustion result in?

A

Smoky yellow flame and less energy being released compared to the complete combustion of the same compound

41
Q

How do alkenes react?

A

Most of the time they react via addition reactions. The carbon – carbon double bond opens up to leave a single bond and the new atom is added to each carbon
R H Y H
C=C + X-Y —> R-C-C-H (R= carbon chain)
H H H X

42
Q

what is Hydrogenation?

A

Addition of hydrogen

43
Q

Hydrogenation of alkenes

A

Hydrogen can react with the double bonded carbons to open up the double bond and form the equivalent, saturated, alkane. The alkene is reacted with hydrogen in the presence of a catalyst.
R H H H
C=C + H2 —> R-C-C-H
H H H H

44
Q

Halogens reacting with alkenes

A

Alkenes will also react in addition reactions with halogens such as bromine, chlorine and iodine.
The molecules formed are saturated with the C=C carbons each becoming bonded to a halogen atom
H H H Br
C=C + Br2 —> H-C-C-H
H H Br H

45
Q

What test can be used to differentiate between alkanes and alkenes?

A

Shaken bromine water

46
Q

What colour does an alkene go in the shaken bromine water test?

A

Colourless

47
Q

What colour does an alkane go in the shaken bromine water test?

A

Stays Orange

48
Q

Steam reacting with alkene it form alchohols

A

When alkenes react with steam, water is added across the double bond and an alcohol is formed
E.g. ethanol can be made by mixing Ethene with steam and then passing it over a catalyst
H H H H
C=C + H2O —> H-C-C-O-H
H H Br H

49
Q

What are monomers?

A

Small molecules with a double bond that can join together to make polymers

50
Q

What are plastics made up of?

A

Long chain molecules called polymers

Usually carbon based and their monomers are often alkenes

51
Q

Polymerisation

A

When lots of small molecules called monomers join together

Usually needs high pressure and a catalyst

52
Q

Addition polymerisation

A

Monomers that make up addition polymers have double covalent bonds
Lots of unsaturated monomers (alkenes) can open up their double binds and join together to form polymer chains

53
Q

Addition polymerisation reaction example

A

H H H H
n( C=C ) —> -(-C-C-)-
H H H H n
Many single Ethenes —> poly(ethene)

54
Q

Homologous series

A

A group of chemicals that react in a similar way because they have the same functional group
E.g alcohols and alkanes

55
Q

General formula of an alcohol

A

CnH2n+1OH

56
Q

Methanol formula

A

CH3OH
H
H-C-O-H
H

57
Q

Ethanol formula

A

C2H5OH

58
Q

Propanol formula

A

C3H7OH

59
Q

Butanol formula

A

C4H9OH

60
Q

What do all alcohols have?

A

An -OH functional group

61
Q

Alcohol characteristics

A

Flammable
Undergo complete combustion in air to produce CO2 and H2O
Soluble in water
React with sodium to produce hydrogen
Can be oxidised to produce carboxylic acid

62
Q

Carboxylic acid

A
Different alcohols form different carboxylic acids
Methanol is oxidised to methanoic acid
Ethanol to ethanoic acid
All have -COOH
homologous series of compounds
63
Q

What are alcohols used as?

A
  • Methanol and ethanol are used as solvents in industry as they can dissolve most things water can dissolve but they can also dissolve substances that wate can’t dissolve e.g. hydrocarbons, oils and fats
  • first 4 alcohols are used as fuels e.g. ethanol as a fuel in spirit burners
64
Q

Fermentation

A

A way of making ethanol

1) fermentation uses an enzyme in yeast to convert sugars into ethanol. Carbon dioxide is also produced. The reaction occurs in solution so the ethanol produced is aqueous
2) Fermentation happens fastest at a temperature of around 37 °C, in a slightly acidic solution and under anaerobic conditions (no oxygen)
3) Under these conditions the enzyme in yeast works best to convert the sugar to alcohol. If the conditions were different, for example a lower pH/higher temperature or higher pH/ lower temperature, the enzyme could be denatured (destroyed) or could work at a much slower rate.

65
Q

Methanoic acid formula

A

HCOOH

      O
      ||   
H-C
      |
    OH
66
Q

Ethanoic acid formula

A

CH3COOH

67
Q

Propanoic acid formula

A

C2H5COOH

68
Q

Butanol acid formula

A

C3H7COOH

69
Q

What is formed when a carboxylic acid reacts with a carbonate?

A

Carbon dioxide

70
Q

What do carboxylic acids form when dissolved in water?

A

Acidic solutions

71
Q

What is formed when carboxylic acids react with alcohols in the presence of an acid catalyst?

A

They form esters

72
Q

How are esters formed?

A

When carboxylic acids and alcohols react

73
Q

What is functional group found in esters?

A

-COO

74
Q

How are esters named?

A

The prefix of the alcohol with -yl as a suffix and the prefix of the acid with-oate as the suffix. For example, ethanol and ethanoic acid would react to form ethyl ethanoate

75
Q

What are properties of esters?

A

They are volatile and have distinctive smells

76
Q

Formation of esters equation

A

Alcohol + carboxylic acid —> ester + water

77
Q

What is a condensation polymerisation reaction?

A

Monomers join together to form large polymer molecules and lose small molecules such as water

78
Q

What do amino acids form when they join by condensation polymerisation?

A

Polypeptides and water

79
Q

What process do amino acids go through to form larger molecules?

A

Condensation polymerisation

80
Q

What is dna?

A

Stores the genetic material of living organisms

81
Q

What is dna made up of?

A

4 nitrogen bases, a phosphate and a sugar

82
Q

What are the 4 nitrogen bases in dna?

A

G C A T

83
Q

What is a nucleotide?

A

Half of one rung of DNA- A phospate, a sugar and a base

84
Q

Polymers of sugar

A

Starch and cellulose

85
Q

What organism makes starch and cellulose?

A

Plants

86
Q

What type of molecules are starch, cellulose and sugars?

A

Carbohydrates

87
Q

Sumo,e sugars can form polymers

A

Sugars are small molecules containing carbon, oxygen and hydrogen
Sugars can react together through polymerisation reactions to form larger polymers