Chains, Energy and Resources - Alcohols, Halogenoalkanes and Analysis Flashcards Preview

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Flashcards in Chains, Energy and Resources - Alcohols, Halogenoalkanes and Analysis Deck (104):
1

What are the two different methods used to make ethanol?

Ethanol can be made by either the hydration of ethene or the fermentation of sugars.

2

What conditions does the hydration of steam to make ethanol require?

The hydration of ethene involves using steam in the presence of a phosphoric acid catalyst at 300oC and 60atm.

3

TRUE or FALSE

The hydration of ethene to produce ethanol is a reversible reaction?

TRUE!

The hydration of ethene reaction is reversible so conversion of ethene is incomplete.

4

In the hydration of ethene to make ethanol, each time the reagent are passed through the detector, what percentage of materials are converted?

Each time reagents are passed through the reactor only 5% of ethene is converted.

5

What conditions are required for the fermentation of carbohydrates to produce ethanol?

The fermentation of carbohydrates is carried out in a solution at relatively low termperatures in the presence of yeast and catalysed by the yeast enzyme zymase.

6

In fermentation, carbohydrates are converted into what products?

In fermentation, carbohydrates are converted to ethanol and CO2.

7

The toxic nature of alcohol means that in a fermentation reaction to produce ethanol, the alcohol can only get to around ...... or the enzyme will stop functioning.

The toxic nature of alcohol means that it can only get to around 14% or the enzyme will stop functioning.

8

TRUE or FALSE

The fermentation of carbohydrates into enthanol is an aerobic process?

FALSE!

The fermentation of carbohydrates into ethanol is an anaerobic process.

9

What products could form if oxygen was present in fermentation?

The absence of oxygen prevents the formation of ethanal or ethanoic acid.

10

What products can ethanol be used in?

Ethanol can be used in perfumes, aftershaves and cleaning fluids. It is also an important solvent in methylated spirits.

11

What ingredients are used to make beer?

Barley, hops and water are combined with yeast to produce beer.

12

The vast majority of ethanol produced in the USA is used for what?

The vast majority of ethanol produced in the USA is used as fuel.

13

What are methylated spirits used for?

Methylated spirits is used as a solvent for removing paint or ink stains from clothing and as a fuel in spirit burners and camping stoves.

14

Which alcohol is used as an additive in high performance racing cars?

Methanol is an additive in high performance racing cars.

15

What is the strongest type of intermolecular force?

Hydrogen bonds are the strongest type of intermolecular force.

16

The relatively high melting and boiling points of alcohols are due to what?

The relatively high melting and boiling points of alcohols are due to the presence of hydrogen bonds.

17

Define volatility.

Volatility is the ease that a liquid turns into a gas.

18

Why do alcohols have a lower volatility than alkanes of a similar mass?

Alcohols have a lower volatility than alkanes of a similar mass due to the presence of hydrogen bonds.

19

Why are alcohols soluble in water?

Alcohols are soluble in water due to the presence of hydrogen bonds.

20

TRUE or FALSE

A volatile chemical evaporates readily into the atmosphere at standard RTP?

TRUE!

A volatile chemical evaporates readily into the atmosphere at standard RTP.

21

Solubility of alcohols ....... as chain length increases.

Solubility of alcohols decreases as chain length increases.

22

Why does the solubility of alcohols decrease as chain length increases?

The solubility of alcohols decreases as chain length increaes because a larger part of the molecule is non-polar.

23

Alcohols can be classified as primary, secondary or tertiary depending on what?

Alcohols can be classified as primary, secondary or tertiary depending on the number of alkyl groups attached to the carbon carrying the alcohol group.

24

What characterises a primary alcohol?

A primary alcohol has a carbon atom with no alkyl groups or bonded to one alkyl group.

25

What characterises a secondary alcohol?

A secondary alcohol has an alcohol group attached to a carbon attached to two alkyl groups.

26

What characterises a tertiary alcohol?

A tertiary alcohol has an alcohol group attached to a carbon atom bonded to three alkyl groups.

27

TRUE or FALSE

Tertiary alcohols can be oxidised?

FALSE!

Only primary and secondary alcohols can be oxidised.

28

What conditions would be need for the oxidation of primary and secondary alcohols?

For the oxidation of primary and secondary alcohols, a suitable oxidising agent would be a solution containing acidified dichromate ions H+/Cr2O7 & H2SO4.

29

What colour are the acidified dichromate ions, H+/Cr2O7 & H2SO4 at the beginning of the oxidation reaction?

The acidified dichromate ions, H+/Cr2O7 & H2SOwill begin the reaction orange.

30

What colour will the acidified dichromate ions, H+/Cr2O7 & H2SO4 be at the end of the oxidation reaction?

The acidified dichromate ions, H+/Cr2O7 & H2SO4 will be green at the end of the oxidation reaction.

31

Primary alcohols are oxidised to ......

Primary alcohols are oxidised to aldehydes.

32

Which symbol is used to represent an oxidising agent?

The symbol [O] is used to represent an oxidising agent.

33

If a primary alcohol is oxidised completely is will become a ......

If a primary alcohol is oxidised completely, it will become a carboxylic acid.

34

How do we prevent the formation of a carboxylic acid in oxidation reactions in the lab?

When preparing aldehydes in the lab, the aldehyde needs to be distilled off to prevent in from forming a carboxylic acid.

35

Define reflux.

Reflux is the continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry.

36

Secondary alcohols can be oxidised to form......

Secondary alcohols can be oxidised to form ketones.

37

What are tertiary alcohols oxidised to form?

Tertiary alcohols are resistant to oxidation.

38

An ester is formed from the addition of what two types of compound?

An ester is formed from the reaction between an alcohol and a carboxylic acid.

39

What is the catalyst for esterification reactions?

Concentrated H2SO4 is the catalyst for esterification reactions.

40

When naming an ester, which part of the name does the alcohol provide?

When naming an ester, the alcohol provides the alkyl part of the name.

41

When naming an ester, which part of the name does the carboxylic acid provide?

When naming an ester, the carboxylic acid provides the alkanoate part of the name.

42

What is an ester linkage?

An ester linkage is C=O

                           l

                           O

43

The formation of esters releases which molecule?

The formation of esters releases a water molecule.

44

What are esters used for?

Esters are used as adhesives and solvents in the chemical industry and the flavours and fragrances of different esters are widely used to produce food flavourings and perfumes.

45

Which ester gives the smell of orange?

Octyl ethanoate gives the smell of orange.

46

Which ester gives the smell of banana?

Pentyl ethanoate gives the smell of banana.

47

How do you make an ester?

To make an ester, add equal amounts of carboxylic acid and alcohol and place in a water bath at 80oC for 5 minutes then pour into a beaker of cold water, the ester is the oil floating on top.

48

An alcohol can be dehydrated to form an alkene in the presence of what catalyst?

An alcohol can be dehydrated to form an alkene in the presence of an acid catalyst such as concentrated H3PO4 or H2SO4.

49

To what temperature and for how long does an alcohol need to be heated in a dehydration reaction?

Alcohol is heated under reflux in the presence of an acid catalyst for ~40 minutes.

50

Define dehydration.

Dehydration is an elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule.

51

Halogenoalkanes is the past have been used for what purposes?

In the past, halogenoalkanes have been used as refrigerants, aerosol propellents, degreasing agents and dry cleaning solvents.

52

Why are halogenoalkanes no longer used in aerosols?

Halogenoalkanes are no longer used in aerosols due to damage to the ozone layer.

53

What is the general formula of halogenoalkanes?

The general formula of halogenoalkanes is CnH2n+1X

54

TRUE or FALSE

The carbon-halogen bond is non-polar?

FALSE!

The carbon-halogen bond is polar.

55

The electronegativity of halogens decreases ...... the group?

The electronegativity of halogens decreases down the group.

56

The electronegativity of halogens increases ........ the group?

The electronegativity of halogens increases up the group.

57

Define hydrolysis.

Hydrolysis is the reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds.

58

Define nucleophilic substitution.

Nucleophilic substitution is a type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

59

During hydrolysis of a halogenoalkane, what is the halogen replaced by?

During hydrolysis of a halogenoalkane, the halogen is replacecd by a hydroxide ion to form alcohol.

60

How can the rate of hydrolysis be calculated?

The rate of hydrolysis can be calculated by doing 1/time taken for the precipitate to occur.

61

What two factors affect the rate of hydrolysis of the halogenoalkanes?

The polarity and the bond enthalpy.

62

How does the polarity of the carbon-halogen bond affect the rate of hydrolysis of halogenoalkanes?

The polarity of the carbbon-halogen bond affects the rate of hydrolysis because the most polar attracts the nucleophile the most readily.

63

How does the bond enthalpy affect the rate of hydrolysis of halogenoalkanes?

The bond enthalpy of the carbon-halogen bond affects the rate of hydrolysis because the bond with the lowest bond enthalpy, i.e the weakest should be broken the easiest.

64

Which is more important in terms of hydrolysis: polarity or bond enthalpy?

Bond enthalpy is more important than polarity in terms of hydrolysis of bonds.

65

What is poly(tetrafluoroethene) or PTFE also known as?

poly(tetrafluoroethene) or PTFE is also known as Teflon.

66

What did Thomas Midgley develop as an alternative to ammonia, chloromethane and sulphur dioxide for refrigeratns?

Midgley developed freon, or CCl2F2 as an alternative as it was unreactive and non-toxic.

67

Why are CFCs so stable?

CFCs are so stable due to the strength of the carbon-halogen bond.

68

What is now used instead of CFCs as refrigerants?

CFCs have since been replaced by carbon dioxide as refrigerants.

69

What is/was the problem with CFCs?

CFCs remain stable until they reach the Earth's stratosphere where they break down in the presence of ultraviolet radiation to form chlorine radicals, chlorine radicals are thought to catalyse the breakdown of the ozone layer.

70

What were CFCs originally developed as?

CFCs were originally developed as refrigerants, propellants, blowing agents and solvents for the dry cleaning idustry.

71

What are now being used as alternatives to CFCs?

HFCs and HCFCs are being used as alternatives to CFCs.

72

How is the percentage yield calculated?

actual amount in mol

Percentage yield = ---------------------------------                X 100

theoretical amount of product

73

What is the purpose of percentage yield?

When writing equations, it is assumed that all the reactants are converted to products, percentage yield finds out how true that is.

74

Define a limiting reagent.

A limiting reagent is the substance in a chemical reaction that runs out first.

75

Define the atom economy.

Atom economy considers not only the desired product, but also the by-products, describes the efficiency of ALL the atoms involved in a chemical reaction.

76

What is the percentage atom economy for addition reactions?

Addition reactions have 100% atom economy.

77

What percentage atom economy do substitution reactions and elimination reactions have?

Substitution and elimination reactions have <100% atom economy.

78

The amount of vibration of a bond when absorbing infra red radiation depends on what?

The amount of vibration depends on bond strength, length and the mass of each atom involved in the bond.

79

Between which frequencies do most bonds vibrate?

Most bonds vibrate at a frequency between 300-4000cm-1.

80

At what wavelength does a C-O bond found in alcohols, esters and carboxylic acids vibrate?

A C-O bond found in alcohols, esters and carboxylic acids will vibrate at a wavelngeth on 1000-1300cm-1.

81

At what wavelength will a C=O bond found in aldehydes, ketones, carboxylic acids, esters and amides vibrate?

A C=O bond found in aldehydes, ketones, carboxylic acids, esters and amides will vibrate at a wavelength of 1640-1750cm-1.

82

At what wavelength will a C-H bond found in organic compounds vibrate?

A C-H bond will vibrate at a wavelength of 2850-3100cm-1.

83

At what wavelength will a O-H bond found in carboxylic acids vibrate?

An O-H bond found in carboxylic acids will vibrate at a wavelength of 2500-3300cm-1.

84

At what wavelength will an N-H bond found in amines and amides vibrate?

An N-H bond found in amines and amides will virbrate at a wavelength of 3200-3500cm-1.

85

At what wavelength will an O-H bond found in alcohols and phenols vibrate?

An O-H bond found in alcohols and phenols will vibrate at a wavelength of 3200-3550cm-1.

86

Which bond(s) vibrate at a wavelength of 1000-1300cm-1?

The C-O bond found in alcohols, esters and carboxylic acids vibrates at a wavelength of 1000-1300cm-1.

87

Which bond(s) vibrate at a wavelength of 1640-1750cm-1?

The C=O in aldehydes, ketones, carboxylic acids, esters and amides vibrates at a wavelength of 1640-1750cm-1.

88

Which bond(s) vibrate at a wavelength of 2850-3100cm-1?

The C-H bond found in organic compounds vibrates at a wavelength of 2850-3100cm-1.

89

Which bond(s) vibrate with a wavelenth of 2500-3300cm-1?

The O-H bond found in carboxylic acids vibrates at a wavelength of 2500-3300cm-1.

90

Which bond(s) vibrate at a wavelength of 3200-3500cm-1?

The N-H bond found in amines and amides vibrates at a wavelength of 3200-3500cm-1.

91

Which bond(s) vibrate at a wavelength of 3200-3550cm-1?

The O-H bond found in alcohols and phenols vibrates at 3200-3550cm-1.

92

Where is there a peak in most organic compounds and why?

Most organic compounds produce a peak at approximately 3000cm-1 due to the absorption by C-H bonds.

93

Who developed the first mass spectrometer?

JJ Thomson developed the first mass spectrometer.

94

In what year was JJ Thomson awarded the Nobel prize for his work?

JJ Thomson was awarded the Nobel prize in 1906 for his work.

95

What are the uses of mass spectrometry?

Mass spectrometry is used to:

  • identify unknown compounds
  • determine the abundance of each isotope in an element
  • gain further information about the structure and chemical properties of molecules.

96

What is mass spec used in?

Mass spectrometry is used in:

  • monitoring the breath of patients during surgery whilst under anaesthetic
  • detecting banned substances such as steroids in athletics
  • analysing molecules in space
  • detecting traces of toxic chemicals in contaminated marine life

97

How does a mass spectrometer work?

A sample is added via the sample inlet. The molecules are then converted to ions by an ionisation source and these ions are propelled into a mass analyser. The ions are separated according to their mass-to-charge ratio and are detected which then generates a mass spec by the computer.

98

What is the molecular ion?

The molecular ion, or M+, is the positive ion formed in mass spectrometry when a molecule loses an electron.

99

What is the best method for ionisation in a mass spectrometer?

Several different methods can be used for ionisation, but electron impact is the oldest and best established method.

100

What is fragmentation in mass spectrometry?

Fragmentation is the process in mass spectrometry that causes a positive ion to split into pieces, one of which is the fragment ion.

101

Define a radical.

A radical is a species with an unpaired electron.

102

Define an electrophile.

An electrophile is an electron pair acceptor.

103

Define a nucleophile.

A nucleophile is an electron pair donor.

104