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a-level oxford chem > 3.3.9 Carboxylic Acids and Derivatives > Flashcards

3.3.9 Carboxylic Acids and Derivatives Flashcards

1
Q

Draw the functional group of esters

A
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2
Q

State the prefix / suffix of esters

A

-yl –oate

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3
Q

Draw the functional group of acyl chlorides

A
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4
Q

State the suffix of acyl chlorides

A

-oyl chloride

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5
Q

Draw the functional group of amides

A
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6
Q

State the suffix of amides

A

-amide

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7
Q

Draw the functional group of acid anhydrides

A
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8
Q

State the suffix of acid anhydrides

A

-oic anhydride

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9
Q

Weak acids partially dissociate into ______ ion and ___ ion

A

Partially dissociate into carboxylate ion and H+ ion

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10
Q

Write an equation to represent the dissociation of weak acids. Draw the displayed formula of the molecules.

A
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11
Q

When carboxylic acids react with carbonates, what gas is formed?

A

CO2

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12
Q

When carboxylic acids react with alcohols, what do they form?

A

Esters

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13
Q

What functional group do esters have?

A

-COO-

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14
Q

Describe how esters are made

A
  • Esterification
  • Made by heating carboxylic acid with alcohol in presence of strong acid catalyst
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15
Q

Give an example of an acid catalyst that can be used in esterification

A

Concentrated sulfuric acid

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16
Q

Write an equation for when alcohols react with carboxylic acids. Draw the molecules in displayed formula.

A
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17
Q

Write an equation for when ethanoic acid reacts with ethanol. Draw the molecules in displayed formula. State the name of the ester.

A

ethyl ethanoate

1st part = alcohol

2nd part = carboxylic acid

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18
Q

Name 4 uses of esters

A
  • Perfumes
    • Have sweet swell
  • Food flavourings
    • Flavour drinks and sweets
  • Solvents
    • Glues, drinking inks
  • Plasticisers
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19
Q

Explain why esters make good solvents

A
  • Are polar liquids so lots of polar organic compounds will dissolve in them
  • Got low boiling points = evaporate easily from mixtures
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20
Q

Explain how esters act as plasticisers

A

Added to plastics during polymerisation to make plastic more flexible

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21
Q

What happens to plastics over time after they have undergone polymerisation?

A

Over time, plasticiser molecules escape and plastic becomes brittle and stiff

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22
Q

How do you convert an ester into an alcohol?

A

Hydrolysis

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23
Q

Why is water not used when hydrolysing esters to alcohols? Name what substances you can use instead.

A

Using water to split up a substance is very slow, so an acid or alkali is often used to speed it up

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24
Q

Esters are Hydrolysed to form Alcohols

Name 2 types of hydrolysis that can be used

A
  • Acid Hydrolysis
  • Base Hydrolysis
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25
Q

Describe how you can use acid hydrolysis to form an alcohol

A
  • Reflux ester with dilute acid e.g. hydrochloric or sulfuric
    • Splits ester in acid and alcohol
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26
Q

Describe how you can use base hydrolysis to form an alcohol

A
  • Refluxing ester with dilute alkali e.g. sodium hydroxide
  • Get carboxylate ion and an alcohol
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27
Q

Write an equation to show ethyl ethanoate undergoing acid hydrolysis. Draw molecules in displayed formula.

A
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28
Q

Write an equation to show ethyl ethanoate undergoing base hydrolysis. Draw molecules in displayed formula.

A
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29
Q

What are fatty acids essentially?

A

long chain carboxylic acids

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30
Q

What is formed when fatty acids combine with glycerol?

A

Esters = fats and oils

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31
Q

Fatty acids can be ______ or _______

A

Fatty acids can be saturated (no double bonds) or unsaturated (C=C double bonds)

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32
Q

Most of fat or oil is made from _____ _____ chains

A

fatty acid

They give them many of their properties

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33
Q

What type of hydrocarbon chains do animal fats have?

A

Have mainly saturated hydrocarbon chains

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34
Q

What type of hydrocarbon chains do vegetable oils have?

A

Have unsaturated hydrocarbon chains

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35
Q

Explain why animal fats are solid at room temperature

A
  • Saturated hydrocarbon chains fit neatly together = increase van der Waals forces between them
  • Means you need higher temperature to melt them
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36
Q

Explain why vegetable oils are liquid at room temperature

A
  • Double bond means mean chains are bent & don’t pack together well = ↓ van der Waals forces
  • Easier to melt
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37
Q

Draw an ester of glycerol and fatty acids

A
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38
Q

Describe how you can hydrolyse vegetable oils and animal fats and what this produces

A
  • By heating ester with sodium hydroxide
  • Produces glycerol, fatty acids and soap = sodium salt
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39
Q

Why are vegetable oils converted into biodiesel, before they can be used as vehicle fuels?

A

Vegetable oils can’t be burned directly in engines

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40
Q

Describe how vegetable oils are converted into biodiesel

A
  • Involves reacting them methanol, using potassium hydroxide as a catalyst
  • Get mixture of methyl esters of fatty acids
    • = biodiesel
41
Q

Write an equation representing vegetable oils being converted into biodiesel. Draw molecules in displayed formula.

42
Q

State the functional groups of acyl chlorides

43
Q

Name this molecule

44
Q

Name this molecule

45
Q

Name 4 substances acyl chlorides react with

A
  • Water
  • Alcohols
  • Ammonia
  • Primary amines
46
Q

Describe how acyl chlorides react with water. Include its product.

A

A vigorous reaction with cold water, producing a carboxylic acid

47
Q

Write an equation representing how ethanoyl chloride reacts with water. Draw the molecules in displayed formula.

48
Q

Describe how acyl chlorides react with alcohols. Include its product.

A

A vigorous reaction at room temperature, producing an ester

49
Q

Write an equation representing how ethanoyl chloride reacts with methanol. Draw the molecules in displayed formula.

50
Q

Describe how acyl chlorides react with ammonia. Include its product.

A

A violent reaction at room temperature, producing an amide

51
Q

Write an equation showing how ethanoyl chloride reacts with ammonia. Draw the molecules in displayed formula.

52
Q

Describe how acyl chlorides react with primary amines. Include its product.

A

A violent reaction at room temperature, producing an N-substituted amide

53
Q

Write an equation to show how ethanoyl chloride reacts with methylamine. Draw the molecules in displayed formula.

54
Q

What happens in each reaction with acyl chlorides?

A

Cl is substituted by oxygen or nitrogen group & misty fumes of hydrogen chloride are given off

55
Q

Acyl chlorides and ___ _______ react in the same way

A

Acid Anhydrides

56
Q

What are acid anhydrides made from?

A

2 identical carboxylic acid molecules

57
Q

State how you would name an acid anhydride if you know the name of the carboxylic acid

A

take away ‘acid’ and add ‘anhydride’

58
Q

Write an equation representing 2 ethanoic acids combining to form an acid anhydride. Draw the molecules in displayed formula.

59
Q

Describe how reactions of acyl chlorides differ from reactions of acid anhydrides

A

Almost the same as those of acyl chlorides but reactions a less vigorous & get carboxylic acid formed instead of HCl

60
Q

Write an equation representing how ethanoic anhydride reacts with methanol

61
Q

What mechanism reaction are acyl chloride reactions?

A

Nucleophilic Addition-Elimination

62
Q

Explain why acyl chlorides are easily attacked by nucleophiles

A

Both chlorine and oxygen draw electrons towards themselves, so carbon has slight positive charge

63
Q

Draw the mechanism for nucleophilic addition-elimination reaction between ethanoyl chloride and methanol

64
Q

Draw the nucleophile for water

65
Q

Draw the nucleophile for ammonia

66
Q

Draw the mechanism for when methyamine reacts with ethanoyl chloride

67
Q

Aspirin is an ___

68
Q

Describe how aspirin is made

A

Made by reacting salicylic acid with ethanoic anhydride or ethanoyl chloride

69
Q

Why is ethanoic anhydride used in industry to make aspirin instead of ethanoyl chloride?

A
  • Cheaper than ethanoyl chloride
  • Safer to use than ethanoyl chloride as it’s less corrosive, reacts more slowly with water, and doesn’t produce dangerous hydrogen chloride fumes
70
Q

Purifying Organic Compounds

State when you can use separation

A

If product is insoluble in water, can use separation to remove any impurities that do dissolve in water

71
Q

Purifying Organic Compounds

Describe a method for separation

A
  1. Once reaction to form product is completed, pour the mixture into separating funnel & add water
  2. Shake funnel and then allow it to settle
    • Organic layer and aqueous layer (which contains any water soluble impurities) are immiscible (they don’t mix) so separate out into 2 distinct layers
  3. Can open tap and run each layer off into a separate container
72
Q

Purifying Organic Compounds

State a method you can use to separate your product and impurities if they are both soluble in water

A

Solvent extraction

(similar separation method)

73
Q

Purifying Organic Compounds

Describe a solvent extraction method

A
  1. Take organic solvent in which the product is more soluble in than it is in water
  2. Add it to impure product solution & shake well
  3. Product will dissolve into organic solvent = leaving impurities dissolved in water
  4. Solvent containing product can be run off using separating funnel
74
Q

If you use separation to purify a product, why does the product have to be dried?

A

∵ organic layer will end up containing trace amounts of water

75
Q

Describe how you can remove water from a purified product by drying it

A
  1. Add anhydrous salt (e.g. magnesium sulfate or calcium chloride)
  2. When you first add salt to organic layer = clumps together
    • Keep adding drying agent until it disperses evenly when you swirl the flask
  3. Filter mixture to remove solid drying agent
    • Pop a piece of filter paper into a funnel that’s in a flask and pour mixture into filter paper
76
Q

When removing water from a purified product by drying it, why is anhydrous salt used?

A

Salt is used as drying agent = binds to any water present to become hydrated

77
Q

Describe a way, other than by drying it, to remove impurities from a product of a reaction.

A
  • Can remove some of these by washing the product
    • (Adding another liquid and shaking)
  • ∵ product can be contaminated with leftover reagents or unwanted side products
78
Q

Describe how you could remove acid from an impure product in solution.

A
  • Aqueous sodium hydrogencarbonate can be added to impure product in solution to remove acid from it
  • Acid reacts with sodium hydrogencarbonate to give CO2 gas and organic product can be removed using separating funnel
79
Q

How can volatile liquids can be purified?

A

By distillation

80
Q

Describe how distillation works

A
  • Works by gently heating a mixture in distillation apparatus
  • Substances will evaporate out of mixture in order of increasing boiling point
81
Q

Describe how you can purify volatile liquids by distillation

A
  1. Connect a condenser to round bottomed flask containing your impure product in solution
  2. Place thermometer in neck of flask so bulb sits next to entrance to condenser
    • Temperature on thermometer will show boiling point of substance that’s evaporating at any given time
  3. Heat impure product
  4. When product you want to collect boils, place a flask at open end of condenser to collect your pure product
82
Q

When purifying volatile liquids by distillation, why should you use an electric heater?

A

Many organic chemicals are flammable

83
Q

State how organic solids can be purified

A

Recrystallisation

84
Q

Describe how organic solids can be purified via recrystallisation

A
  1. Dissolve impure solid in minimum hot solvent
    • Don’t add too much solvent = want saturated solution of impure product
  2. Filter hot solution through heated funnel
    • To remove any insoluble impurities
  3. Leave solution to cool down slowly
    • Crystals of product will form as it cools
  4. Filter mixture under reduced pressure
    • To remove liquid containing soluble impurities from crystals
  5. Wash crystal with ice-cold solvent
    • To remove any soluble impurities from their surface
  6. Leave your purified crystals to dry
85
Q

Describe how you could remove liquid containing soluble impurities from crystals by filtering a mixture under reduced pressure

A

Pour mixture into filter paper lined Büchner funnel (flat bottomed funnel with holes in base) that’s sitting in side-arm flask attached to vacuum line

86
Q

Recrystallisation

Why does crystals of product form as the solution cools?

A
  • As solution cools, solubility of product falls
  • Reaches point where it can’t stay in solution = forms pure crystals
87
Q

What are good indicators of purity?

A

Melting and boiling points

88
Q

Pure substances have ______ melting and boiling points

89
Q

What happens to substance’s melting and boiling point when it’s impure?

A

Melting point is lowered and boiling point is raised

90
Q

What happens substance’s melting and boiling point when it’s very impure?

A

Melting and boiling will occur across a wide range of temperatures

91
Q

What type of apparatus can you use to accurately determine the melting point of an organic solid?

A

Melting point apparatus

92
Q

Describe how you can use melting point apparatus to accurately determine the melting point of an organic solid

A
  1. Pack small sample of solid into glass capillary tube and place it inside the heating element
  2. Increase the temperature until sample turns from solid to liquid
  3. Measure a melting range (range of temperatures from where solid begins to melt to where it has melted completely)
  4. Can look up the melting point of substance in data books and compare it to your measurements
  5. Impurities in sample will lower the melting point and broaden the melting range
93
Q

Pure substances melt _____

94
Q

Give an observation that occurs during esterification

A

Sweet smell/oily layer

95
Q

Recrystallisation

Why shouldn’t you add too much solvent when dissolving the solid?

A

Want saturated solution of impure product

96
Q

Recrystallisation

Why do you filter hot solution through a heated funnel?

A

To remove any insoluble impurities

97
Q

Recrystallisation

Why do you leave the solution to cool down slowly?

A

More crystals of product will form as it cools/decreases solubility of solid

98
Q

Recrystallisation

Why do you filter the mixture under reduced pressure?

A

To remove liquid containing soluble impurities from crystals

99
Q

Recrystallisation

Why do you wash the crystal with ice-cold solvent?

A

To remove any soluble impurities from their surface

a-level oxford chem (34 decks)

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