Organic Compounds Flashcards Preview

Chemistry > Organic Compounds > Flashcards

Flashcards in Organic Compounds Deck (142):
1

How is methane produced?

By anaerobic bacterial decomposition of either animal waste or vegetation

2

Why is the concentration of methane a cause of concern?

Global warming

3

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

Stronger intermolecular bonds

4

Distinguish between saturated and unsaturated hydrocarbons

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

5

How many pi electrons are there in benzene?

6

6

What is the distribution of pi electrons like in benzene?

Delocalised

7

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

All c-c bonds are of same energy/length
All c-c bonds in benzene are intermediate between single and double in energy

8

What is organic chemistry?

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

9

What is a functional group?

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

10

What kind of bonds do saturated organic compounds have?

Sigma, end on overlap of atomic orbitals

11

What kind of bonding do unsaturated compounds have?

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

12

What are hydrocarbons?

Compounds that contain carbon and hydrogen only

13

What is a homologous series?

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

14

What hydrocarbon when exposed to air forms an explosive mixture?

Methane

15

How are hydrocarbons formed?

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

16

What is the bond angle of a tetrahedral shaped molecule?

109.5 degrees

17

What are the three types of tetrahedral carbon compounds?

Alkanes, alcohols and chloroalkanes

18

What hydrocarbons are saturated?

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

19

What is the functional group of alkanes?

c-c
carbon single bonds

20

What sort of reactions do alkanes undergo?

Substitution reactions

21

Give two uses of alkanes

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

22

What are isomers?

Compounds with the same molecular formula but different structural formula

23

How do isomers differ?

Physical properties eg, boiling points

24

What is an alkyl group?

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

25

What are alcohols?

Similar to alkanes but with a hydrogen replaced by OH

26

What is the functional group of alcohols?

Hydroxyl group
OH

27

How do you write molecular formula of alcohols?

Alkyl group + OH

28

What is a primary alcohol and give an example

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

29

What are secondary alcohols?

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

30

What are tertiary alcohols?

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

31

What must you always do when naming alcohols?

Indicate position of hydroxyl group

32

What changes alcohols chemistry drastically from corresponding alkanes?

Hydroxyl group

33

Boiling point of alcohols?

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

34

Solubility of alcohols?

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

35

What shape is the functional group of alcohols?

V shaped

36

Explain fermentation

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

37

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

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

38

How do you increase alcohol concentration and give an example

Fermented liquids are distilled eg, wine is distilled to brandy

39

What are the uses of ethanol?

Alcoholic drink [consumption], solvent [perfumes]

40

Why is ethanol a good solvent?

Due to hydrogen bonding

41

Describe hydrogen bonding in alcohols

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

42

Why do ethanol and water mix completely in alcoholic drinks?

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

43

What are chloroalkanes?

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

44

What's another name for chloroform and give a use

Trichloromethane
was used as an anaesthetic

45

Are chloroalkanes soluble in water?

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

46

Boiling point in chloroalkanes

Low boiling points but higher than corresponding alkanes

47

What state are chloroalkanes in room temperature?

Liquids

48

What two chloroalkanes are gases at room temp?

Chloromethane, chloroethane

49

States at room temperature of alkanes

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

50

Why does boiling point of chloroalkanes increase with carbon chain?

Stronger van der waals forces

51

Uses of chloroalkanes and why?

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

52

Give a damaging hydrocarbon in chloroalkanes

Chloromethane - damage to ozone layer

53

Name the carbon compounds that are planar

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

54

Shape of alkenes

Both tetrahedral and planar
Tetrahedral - everywhere but where double bond is

55

Are alkenes saturated or unsaturated?

Unsaturated - double bond

56

What reactions do alkenes undergo?

Addition reactions

57

Uses of ethene

PVC - manufacturing of plastics
Ripening fruit

58

How is ethene prepared?

By dehydrating ethanol

59

How is ethanol prepared?

Hydrating ethene

60

Shape of alkynes?

Both tetrahedral and planar
Tetrahedral - everywhere but where the triple bond is

61

Are alkynes unsaturated or saturated?

Unsaturated - triple bond

62

How is ethyne produced?

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

63

What is aldehydes functional group and where is it positioned?

Carbonyl - CHO
At end of carbon chain

64

Boiling point of aldehydes

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

Solubility aldehydes

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

What state are most aldehydes in room temp?

Liquid except for methanal

67

Formula of methanal

HCHO

68

Uses of aldehydes

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

69

What is benzaldehyde?

It's found in oil of almonds [kernels]

70

How to draw benzaldehyde

Normal benzene + CHO

71

Properties of ketones

Same as aldehydes

72

Difference between ketones and aldehydes?

The hydrogen atom in aldehydes is replaced by an alkyl group

73

Uses of ketones?

Propanone -acetone
Organic solvent such as nail varnish remover

74

What is a carbonyl group?

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

75

Carboxylic acid functional group?

Carboxyl = COOH

76

What are the intermolecular bonding present in carboxylic acids?

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

77

Characteristics of carboxylic acids?

Unpleasant odours such as rancid butter and sweat

78

What are the bonds present in a carboxylic acids

C=O
C-OH

79

Uses of carboxylic acids

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

80

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

More hydrogen bonds between molecules

81

Carboxylic acids - solubility

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

State of matter of carboxylic acids at room temp?

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

83

What are dimers [carboxylic acid]

Groups of two molecules joined together

84

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

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

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

Esters

86

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??

Ethanol
[weaker intramolecular forces]

87

Name the two acidic functional groups that occur in organic compounds

OH
COOH

88

Complete the balanced equation -
C2H6 + Cl2 - uv light >

C2H6 + Cl2 - uv light > C2H5Cl + HCl

89

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

Bonds intermediate between double and single bonds
All carbon-carbon bonds are identical

90

Name an ester that is a structural isomer of propanoic acid

Ethyl methanoate

91

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

Propan-2-ol

92

Ester + HCOOH -> A -> ethene
-Identify A
-how does the geometry around the carbon atoms change in this conversion

Ethanol
Tetrahedral - planar

93

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

Speeds up reaction as it provides ethyl radicals

94

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

Saponification

95

Name the addition polymer formed from propene

Polypropene

96

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

Broken - CO pi bond
Formed - OH, CH

97

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?

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

98

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

Combination of ethyl radicals forms butane

99

Identify the reagent to bring about C2H6 -> CH3CH2Cl

Cl2

100

Identify the reagent to bring about C2H4 -> CH3CH2Cl

HCL

101

Identify the reagent required to bring about C2H4 -> CH2ClCH2Cl

Cl2

102

Draw the structure of A and name when
CH2ClCH2Cl - HCL -> A

CH2 = CHCl
Chloroethene

103

Draw the structure of two repeating units of PVC

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

104

What is the alcohol that forms from propanone is reduced

Propan-2-ol

105

What is the structural difference between a primary and secondary alcohol

Primary - one carbon attached to OH
Secondary - two carbons attaches to OH

106

Identify an isomer of propanone

Propanal

107

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

Broken - C-O C-H
Formed - C=C C-H

108

Describe the bonding in benzene

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

109

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

i ) H2
ii ) Cl2 + UV light

110

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

Cl Cl
H-C-C-H
H H

H H
H C=C H

111

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

Benzaldehyde

112

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

Ethanal

113

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

Fizzing and production of CO2, clear solution formed

114

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

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

115

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

60g / 1000 x100/1 = 6%

116

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

Bromonium ion [show positive charge]

117

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

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

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

Polyethene
[2 ethanes]

119

Name a suitable catalyst for the reduction reactions

Nickel

120

How can alcohol be obtained?

Reduction of aldehydes and ketones using hydrogen and nickel

121

Name the alcohol produced when propanal is reduced

Propan-1-ol

122

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

Propanoic acid

123

Name two features of an elimination reaction

Removal of small molecule [H20]
Change to unsaturated molecule

124

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

Broken - C-H + O-H
Made - C=O

125

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?

Ingestion [drink, food, medicine]

126

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

-polar OH-
-higher molar mass
-intermolecular hydrogen bonds

127

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

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

128

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

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

Name the compound C2H5Cl

Chloroethane

130

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

Substitution

131

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

Aldehyde

132

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

Oxidation

133

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

Dichromate
H+

134

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

Add chlorine
U.V light

135

Account for the greater reactivity of alkenes compared to allanes

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

136

What kind of a reaction is esterification?

Substitution

137

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

Hydrogenation
Producing margarines

138

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

(Chloroalkanes)
Solvent
Anaesthetics
Organic synthesis

139

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

Provides energy for splitting of chlorine into free radicals

140

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

chloromethane
hydrogen chloride

141

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

Methyl radicals combined to form ethane

142

WRITE OUT MECHANISMS

AND WHAT REACTIONS ARE OXIDATION AND REDUCTION