Organic Compounds Flashcards

1
Q

How is methane produced?

A

By anaerobic bacterial decomposition of either animal waste or vegetation

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2
Q

Why is the concentration of methane a cause of concern?

A

Global warming

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3
Q

The boiling points of propane and dodecane are -42 and 216 respectively. Explain why high molecular mass alkanes have high boiling points?

A

Stronger intermolecular bonds

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4
Q

Distinguish between saturated and unsaturated hydrocarbons

A

Saturated hydrocarbons - only single bonds - has max no of hydrogens atom can have
Unsaturated - contains at least one double/triple bond, doesn’t have max amount of hydrogens

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5
Q

How many pi electrons are there in benzene?

A

6

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6
Q

What is the distribution of pi electrons like in benzene?

A

Delocalised

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7
Q

Give evidence to support the fact that pi electrons are delocalised in benzene molecule

A

All c-c bonds are of same energy/length

All c-c bonds in benzene are intermediate between single and double in energy

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8
Q

What is organic chemistry?

A

Study of compounds of carbon other than carbon monoxide, carbon dioxide, carbonates and hydrogencarbonates]

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9
Q

What is a functional group?

A

It’s an atom or group of atoms which is responsible for the characteristic properties of a series of organic compounds

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10
Q

What kind of bonds do saturated organic compounds have?

A

Sigma, end on overlap of atomic orbitals

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11
Q

What kind of bonding do unsaturated compounds have?

A

1 sigma with other bonds of pi type - sideways overlap of p orbitals

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12
Q

What are hydrocarbons?

A

Compounds that contain carbon and hydrogen only

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13
Q

What is a homologous series?

A

A family of organic compounds with the same general formula, similar chemical properties and successive members differing by CH2

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14
Q

What hydrocarbon when exposed to air forms an explosive mixture?

A

Methane

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15
Q

How are hydrocarbons formed?

A

They are naturally occurring and have been formed in the earth over millions of years, eg crude oil

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16
Q

What is the bond angle of a tetrahedral shaped molecule?

A

109.5 degrees

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17
Q

What are the three types of tetrahedral carbon compounds?

A

Alkanes, alcohols and chloroalkanes

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18
Q

What hydrocarbons are saturated?

A

The ones that contain single bonds - alcohol, alkanes and chloroalkanes

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19
Q

What is the functional group of alkanes?

A

c-c

carbon single bonds

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20
Q

What sort of reactions do alkanes undergo?

A

Substitution reactions

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21
Q

Give two uses of alkanes

A

Petrol - 5-10 atoms c atoms
Kerosene [jet due, and central heating fuel]
LPG [liquefied petroleum gas] made up of propane and butane

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22
Q

What are isomers?

A

Compounds with the same molecular formula but different structural formula

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23
Q

How do isomers differ?

A

Physical properties eg, boiling points

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24
Q

What is an alkyl group?

A

It’s an alkanes molecule from which a hydrogen atom has been removed
CH3 - methyl
C2H5 - ethyl

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25
Q

What are alcohols?

A

Similar to alkanes but with a hydrogen replaced by OH

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26
Q

What is the functional group of alcohols?

A

Hydroxyl group

OH

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27
Q

How do you write molecular formula of alcohols?

A

Alkyl group + OH

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28
Q

What is a primary alcohol and give an example

A

When the carbon attached to the hydroxyl group is attached to one other carbon
Eg, propan-1-ol

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29
Q

What are secondary alcohols?

A

When the carbon attached to the hydroxyl group is attached to two other carbons
Eg, propan-2-ol

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30
Q

What are tertiary alcohols?

A

When the carbon attached to the hydroxyl group touches three other carbons
Eg, 2-methylpropan-2-ol

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31
Q

What must you always do when naming alcohols?

A

Indicate position of hydroxyl group

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32
Q

What changes alcohols chemistry drastically from corresponding alkanes?

A

Hydroxyl group

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33
Q

Boiling point of alcohols?

A

Higher than corresponding alkanes
The hydroxyl undergoes hydrogen bonding which results in them having very strong bonds. As a result, it takes more energy to break apart bonds = higher

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34
Q

Solubility of alcohols?

A

It changes as length of carbon chain increases. The OH group is highly polar and if the chain is short, it forces the non polar part [alkyl group] to dissolve in polar substances such as water. If chain becomes too long, the OH group is insignificant and therefore dissolves in non polar substances instead

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35
Q

What shape is the functional group of alcohols?

A

V shaped

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36
Q

Explain fermentation

A

Fruits with glucose have yeast added to them which contains catalyst zymase. Zymase converts glucose into ethanol and carbon dioxide as a result.

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37
Q

Why does fermentation alone not produce drinks greater than 12% v/v

A

Once ethanol reaches this percentage, it kills yeast - stops fermentation

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38
Q

How do you increase alcohol concentration and give an example

A

Fermented liquids are distilled eg, wine is distilled to brandy

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39
Q

What are the uses of ethanol?

A

Alcoholic drink [consumption], solvent [perfumes]

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40
Q

Why is ethanol a good solvent?

A

Due to hydrogen bonding

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41
Q

Describe hydrogen bonding in alcohols

A

Oxygen - partial negative charge [more electronegative]
Hydrogen - partial negative charge
Oxygen in hydroxyl group in one molecule attracts hydrogen in hydroxyl group on neighbouring molecule
This forms strong hydrogen bonds

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42
Q

Why do ethanol and water mix completely in alcoholic drinks?

A

Hydrogen bonds form between hydroxyl groups in ethanol and hydroxyl groups in water

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43
Q

What are chloroalkanes?

A

An alkane with one or more of its hydrogens replaced by chlorines

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44
Q

What’s another name for chloroform and give a use

A

Trichloromethane

was used as an anaesthetic

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45
Q

Are chloroalkanes soluble in water?

A

No, carbon-chlorine bond is polar but not polar enough to make a different to physical properties

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46
Q

Boiling point in chloroalkanes

A

Low boiling points but higher than corresponding alkanes

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47
Q

What state are chloroalkanes in room temperature?

A

Liquids

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48
Q

What two chloroalkanes are gases at room temp?

A

Chloromethane, chloroethane

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49
Q

States at room temperature of alkanes

A

Up to C4 - gases
Next 12 - liquids
Rest - solids

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50
Q

Why does boiling point of chloroalkanes increase with carbon chain?

A

Stronger van der waals forces

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51
Q

Uses of chloroalkanes and why?

A

Used as solvents - lack of polarity, readily dissolve grease and oil which are insoluble in water

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52
Q

Give a damaging hydrocarbon in chloroalkanes

A

Chloromethane - damage to ozone layer

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53
Q

Name the carbon compounds that are planar

A

Alkenes, alkynes, aldehydes, ketones, carboxylic acids, esters, aromatic compounds

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54
Q

Shape of alkenes

A

Both tetrahedral and planar

Tetrahedral - everywhere but where double bond is

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55
Q

Are alkenes saturated or unsaturated?

A

Unsaturated - double bond

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56
Q

What reactions do alkenes undergo?

A

Addition reactions

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57
Q

Uses of ethene

A

PVC - manufacturing of plastics

Ripening fruit

58
Q

How is ethene prepared?

A

By dehydrating ethanol

59
Q

How is ethanol prepared?

A

Hydrating ethene

60
Q

Shape of alkynes?

A

Both tetrahedral and planar

Tetrahedral - everywhere but where the triple bond is

61
Q

Are alkynes unsaturated or saturated?

A

Unsaturated - triple bond

62
Q

How is ethyne produced?

A

Water and calcium carbide bubbles through copper sulfate solution to get rid of impurities like phosphine, ammonia and hydrogen sulfide gas

63
Q

What is aldehydes functional group and where is it positioned?

A

Carbonyl - CHO

At end of carbon chain

64
Q

Boiling point of aldehydes

A

As carbonyl group contains dipole dipole forces they have a higher boiling than corresponding alkanes but a lower boiling point than their corresponding alcohols

65
Q

Solubility aldehydes

A

First few aldehydes are soluble in water [polar] as dipole dipole forces can only force first few carbons to dissolve in a polar substance. Polar carbonyl group forces non polar alkyl group to dissolve however when the chains get longer, carbonyl polar becomes insignificant
H20 can form hydrogen bonds with carbonyl group = low chains

66
Q

What state are most aldehydes in room temp?

A

Liquid except for methanal

67
Q

Formula of methanal

A

HCHO

68
Q

Uses of aldehydes

A

Methanal in water = formalin and is used as an embalming fluid and to preserve biological specimens

69
Q

What is benzaldehyde?

A

It’s found in oil of almonds [kernels]

70
Q

How to draw benzaldehyde

A

Normal benzene + CHO

71
Q

Properties of ketones

A

Same as aldehydes

72
Q

Difference between ketones and aldehydes?

A

The hydrogen atom in aldehydes is replaced by an alkyl group

73
Q

Uses of ketones?

A

Propanone -acetone

Organic solvent such as nail varnish remover

74
Q

What is a carbonyl group?

A

Oxygen attached to a carbon atom by a polar double covalent bond

75
Q

Carboxylic acid functional group?

A

Carboxyl = COOH

76
Q

What are the intermolecular bonding present in carboxylic acids?

A

Hydrogen bonding = high boiling point as it takes a lot of energy to break them

77
Q

Characteristics of carboxylic acids?

A

Unpleasant odours such as rancid butter and sweat

78
Q

What are the bonds present in a carboxylic acids

A

C=O

C-OH

79
Q

Uses of carboxylic acids

A

Methanoic acid - stings of nettles and ants
Ethanoic acid - vinegar
Propanoic and benzoic - preserve foods

80
Q

Why do carboxylic acids have higher boiling point than corresponding alcohol?

A

More hydrogen bonds between molecules

81
Q

Carboxylic acids - solubility

A

Lower members are highly soluble in water due to carboxylic acid group forming hydrogen bonds with water molecule and decreases with length due to insoluble alkyl portion of molecule [polar group becomes insignificant]

82
Q

State of matter of carboxylic acids at room temp?

A

Pure ethanoic acid - liquid but if it falls below 17 degrees it becomes solid = glacial acetic acid
Colourless liquids

83
Q

What are dimers [carboxylic acid]

A

Groups of two molecules joined together

84
Q

After carrying out the lab conversion of ethanol to ethene, how would you test the product to confirm the formation

A

Bromine water - test for unsaturation
Ethanol - Ethene conversion is a saturated [tetrahedral, single bonds] to unsaturated compound therefore if it is ethene, bromine water should go brown - colourless

85
Q

Name the class of organic compounds that are responsible for the scent in fruits such as cherries

A

Esters

86
Q

Three test tubes - ethanol, ethanoic acid and Eugenol but not in that order
It was observed that D evaporated more quickly that either C or E
What is D??

A

Ethanol

[weaker intramolecular forces]

87
Q

Name the two acidic functional groups that occur in organic compounds

A

OH

COOH

88
Q

Complete the balanced equation -

C2H6 + Cl2 - uv light >

A

C2H6 + Cl2 - uv light > C2H5Cl + HCl

89
Q

Explain in terms of bonding why it is more correct to represent the benzene molecule as (diagram of what it is)

A

Bonds intermediate between double and single bonds

All carbon-carbon bonds are identical

90
Q

Name an ester that is a structural isomer of propanoic acid

A

Ethyl methanoate

91
Q

Identify the reactant and transition metal catalyst used to reduce a ketone to an alcohol

A

Propan-2-ol

92
Q

Ester + HCOOH -> A -> ethene

  • Identify A
  • how does the geometry around the carbon atoms change in this conversion
A

Ethanol

Tetrahedral - planar

93
Q

Explain the effect of the presence of tetraethyllead in substitution reaction between ethane and chlorine and ultraviolet light

A

Speeds up reaction as it provides ethyl radicals

94
Q

What name is given to the type of reaction that occurs between sodium hydroxide and an ester

A

Saponification

95
Q

Name the addition polymer formed from propene

A

Polypropene

96
Q

Identify the bonds broken and bonds formed in the conversion of propanone to propan-2-ol

A

Broken - CO pi bond

Formed - OH, CH

97
Q

An isomer of propan-2-ol can be synthesised from an aldehyde. Name the isomer and the aldehyde
How can the aldehyde be converted to the isomer?

A

Isomer - propanol [primary alcohol]
Aldehyde - propanal
Be converted -> H2 + Ni catalyst

98
Q

In the reaction between chlorine gas and ethane in the presence of UV light, explain how the occurrence of another hydrocarbon in the product mixture provides evidence for the mechanism

A

Combination of ethyl radicals forms butane

99
Q

Identify the reagent to bring about C2H6 -> CH3CH2Cl

A

Cl2

100
Q

Identify the reagent to bring about C2H4 -> CH3CH2Cl

A

HCL

101
Q

Identify the reagent required to bring about C2H4 -> CH2ClCH2Cl

A

Cl2

102
Q

Draw the structure of A and name when

CH2ClCH2Cl - HCL -> A

A

CH2 = CHCl

Chloroethene

103
Q

Draw the structure of two repeating units of PVC

A

H Cl H Cl
-C-C-C-C-
H H H H

104
Q

What is the alcohol that forms from propanone is reduced

A

Propan-2-ol

105
Q

What is the structural difference between a primary and secondary alcohol

A

Primary - one carbon attached to OH

Secondary - two carbons attaches to OH

106
Q

Identify an isomer of propanone

A

Propanal

107
Q

List the bonds broken and bonds form in the reaction of ethanol to ethene

A

Broken - C-O C-H

Formed - C=C C-H

108
Q

Describe the bonding in benzene

A

Identical c-c sigma bonds
Delocalised pi bonds formed from six p orbitals
Sigma C-H bonds

109
Q

State the reagents and conditions required to bring about
i ) C2H4 -> C2H6
ii ) C2H6 -> C2H5Cl

A

i ) H2

ii ) Cl2 + UV light

110
Q

The conversion C2H4 -> PVC involves a three-step synthesis. Draw the structures of the two organic intermediates in this synthesis

A

Cl Cl
H-C-C-H
H H

H H
H C=C H

111
Q

Name the aromatic compound found in almond kernels that has the functional group of aldehydes

A

Benzaldehyde

112
Q

Which compound is formed as the primary metabolite of ethanol in the human body?

A

Ethanal

113
Q

Describe what is observed when sodium carbonate is added to a test tube containing an aqueous solution of ethanoic acid

A

Fizzing and production of CO2, clear solution formed

114
Q

Write a balanced equation for the addition of sodium carbonate to ethanoic acid

A

2CH3COOH + Na2CO3 -> 2CH3COONa + H20 + CO2

115
Q

Express the concentration of a one molar solution of ethanoic acid in terms of % w/v

A

60g / 1000 x100/1 = 6%

116
Q

The ionic addition mechanism for the reaction of ethene with bromine water involves the formation of an intermediate ionic species, what is it and be able to draw

A

Bromonium ion [show positive charge]

117
Q

Give the names of the three products that would be formed if the bromine water used in the reaction contained sodium chloride and how does the formation of these three products support the mechanism of ionic addition

A

1,2-dibromoethane
2-bromoethanol
1-bromo-2-chloroethane
Different negative ions [Br-, OH-, Cl-] and water adding on indicates presence of positive intermediate. The formation of the products indicate the positive ion and negative ions added on

118
Q

Name the polymer formed when ethene undergoes addition polymerisation. Draw two repeating units of this polymer

A

Polyethene

[2 ethanes]

119
Q

Name a suitable catalyst for the reduction reactions

A

Nickel

120
Q

How can alcohol be obtained?

A

Reduction of aldehydes and ketones using hydrogen and nickel

121
Q

Name the alcohol produced when propanal is reduced

A

Propan-1-ol

122
Q

Give the name of the organic product of the oxidation of propanal in fehlings solution

A

Propanoic acid

123
Q

Name two features of an elimination reaction

A

Removal of small molecule [H20]

Change to unsaturated molecule

124
Q

List the bonds broken and bonds made in the synthesis of ethanal to ethanol

A

Broken - C-H + O-H

Made - C=O

125
Q

An aldehyde is formed as a metabolite of an alcohol in the human body. How does the aldehyde come to be present in the body?

A

Ingestion [drink, food, medicine]

126
Q

Give two reasons why alcohols have a higher boiling point than corresponding alkane

A
  • polar OH-
  • higher molar mass
  • intermolecular hydrogen bonds
127
Q

Explain why the difference in boiling points between methane and methanol is 226.5K while the difference in boiling points between butane and butanos is only 119K

A

Due to longer carbon chain, effect of OH is less [hydrogen bond is weaker]

128
Q

State three clear pieces of experimental evidence which support the free radical substitution mechanism

A

reaction requires u.v. light of energy high enough to homolyse. For every photon absorbed very many (thousands of) molecules of a product are formed. if u.v is stopped the reaction slows down (stops)
products such as butane / chlorobutane / etc. formed
addition of radical promoters tetramethyl lead, tetra-ethyl lead) alter (speed up) the rate of the reaction

129
Q

Name the compound C2H5Cl

A

Chloroethane

130
Q

What organic reaction type describes the esterification reaction from an alcohol and of a carboxylic acid

A

Substitution

131
Q

Give the name and structure of the intermediate organic compound in the synthesis of an alcohol to a carboxylic acid

A

Aldehyde

132
Q

Identify the type of organic reaction involved from an alcohol to a carboxylic acid

A

Oxidation

133
Q

Identify the inorganic reagents which may be used in the oxidation reactions

A

Dichromate

H+

134
Q

How could the same product of hydrogen chloride and ethene be formed from ethane

A

Add chlorine

U.V light

135
Q

Account for the greater reactivity of alkenes compared to allanes

A

Due to double bond -> electron rich and pi bonds are weak -> easier to react

136
Q

What kind of a reaction is esterification?

A

Substitution

137
Q

What type of reaction is the one from ethene to ethane and give one use of this reaction in industry

A

Hydrogenation

Producing margarines

138
Q

Give one use for the group of compounds to which chloroethane belongs

A

(Chloroalkanes)
Solvent
Anaesthetics
Organic synthesis

139
Q

Explain clearly the role of the ultraviolet light in the reacton between chlorine and methane

A

Provides energy for splitting of chlorine into free radicals

140
Q

Name the two main products of the reaction between chlorine and methane

A

chloromethane

hydrogen chloride

141
Q

Account for traces of ethane found in product mixture of chlorine and methane

A

Methyl radicals combined to form ethane

142
Q

WRITE OUT MECHANISMS

A

AND WHAT REACTIONS ARE OXIDATION AND REDUCTION