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Z/ HIGHER Chemistry > Unit 2: Chapter 5 - Alcohols, Carboxylic Acids and Esters > Flashcards

Unit 2: Chapter 5 - Alcohols, Carboxylic Acids and Esters Flashcards

1
Q

What are alcohols?

A

Alcohols are a homologous series containing the functional group -OH. With The name ending -ol.

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2
Q

What is ethanol commonly used in?

A

Alcoholic drinks.

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3
Q

What is the prefix for 1?

A

Meth

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4
Q

What is the prefix for 2?

A

Eth

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5
Q

What is the prefix for 3?

A

Prop

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6
Q

What is the prefix for 4?

A

But

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7
Q

What is the prefix for 5?

A

Pent

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8
Q

What is the prefix for 6?

A

Hex

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9
Q

What is the prefix for 7?

A

Hept

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10
Q

What is the prefix for 8?

A

Oct

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11
Q

What is this the general formula of alcohols?

A

CnH2N+1OH

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12
Q

What are alcohols containing two hydroxyl groups called?

A

Diols

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13
Q

What are alcohols containing three hydroxyl groups called?

A

Triols

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14
Q

What makes alcohols polar and what does this give rise to?

A

The hydroxyl group makes alcohols polar and this gives rise to hydrogen bonding.

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15
Q

What can hydrogen bonding in alcohols be used to explain?

A

The properties of alcohols including B+M points, viscosity and solubility/miscibility in water.

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16
Q

What is a carboxylic acid?

A

A carboxylic acid is a molecule containing the carboxyl functional group, ─COOH.

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17
Q

what are carboxylic acids also known as?

A

Alkanoic acids.

18
Q

What is the general formula of the carboxylic acids?

A

CnH2nO2

19
Q

What is produced when a carboxylic acid reacts with a metal oxide?

A

A salt + water

20
Q

What is produced when a carboxylic acid reacts with a metal hydroxide?

A

A salt + water

21
Q

What is produced when a carboxylic acid reacts with a metal carbonate.

A

A salt + water + carbon dioxide

22
Q

What are uses of carboxylic acids?

A

Ethyl Ethanoate: Made from Ethanoic acid and when polymerised, used to give the plastic component in paints.

Benzene - 1,4 - dicarboxylic acid: A diacid in the manufacture of polyester.

Hexanedioic acid: Another diacid which is used as a monomer in the production of Nylon.

Benzoic acid: Used as a preservative and antioxidant in fruits.

23
Q

What is an ester?

A

A molecule containing an ester link ( -COO- ).

24
Q

How are esters formed?

A

By a condensation reaction between a carboxylic acid and an alcohol.

25
Q

What is the difference between the reactants and the products in the formation of esters?

A

Both reactants contain hydrogen bonding but the product contains no hydrogen bonding making it immiscible in water.

26
Q

In a condensation reaction two molecules are joined together with the elimination of what?

A

A small molecule. When an ester link is formed by the reaction between a hydroxyl group and a carboxyl
group, the small molecule eliminated is water.

27
Q

What is the water made from in a condensation reaction between a carboxylic acid and an alcohol.

A

The water is made from the H of the hydroxyl group of the alcohol and the -OH group from the acid.

28
Q

What are esters most commonly used for?

A

Esters are used as flavourings and fragrances as many have pleasant, fruity smells. Esters are also used as solvents for non-polar compounds that do not dissolve in water.

29
Q

What does immiscible mean?

A

Incapable of being mixed.

30
Q

Are esters immiscible in water?

A

YES

31
Q

Describe the types of uses of esters?

A
  • Esters are used in a variety of substances. Aspirin contains an ester link which has a bearing of the properties of the aspirin.
  • Nail varnish contains an ester which acts as a solvent and helps dissolve the coloured nail varnish is due to the ester which evaporates quickly after application.
  • Similar to nail varnish car metallic paint is dissolved in an ester solvent to keep the paint liquid. After application the ester evaporates to leave the hard durable metallic paint.
32
Q

What can be used to break down esters to form an alcohol and a carboxylic acid?

A

Hydrolysis

33
Q

What is a negative to using water to hydrolyse an ester?

A

Using water to break up an ester is very inefficient.

34
Q

What is more efficient to use than water to break up an ester and why is this?

A

Acid catalysed hydrolysis which is more efficient as the H+ ion is used as a catalyst. (remember that a dilute acid contains water).

35
Q

What is a negative about using acid catalysed hydrolysis to break up an ester?

A

It is reversible and therefore will be incomplete.

36
Q

What is the most efficient and complete way of break up an ester?

A

Complete hydrolysis by using a strong alkali.

37
Q

What are 2 advantages of Alkaline hydrolysis?

A

1) Alkaline hydrolysis is NOT REVERSIBLE and hence there should be a higher yield of products.
2) It is usually easier to separate the products using alkaline hydrolysis.

38
Q

What is the reaction equation for hydrolysis of an ester by water?

A

Ester + Water = Alcohol and Carboxylic Acid.

39
Q

What is the reaction equation for hydrolysis of an ester by by acid catalysed hydrolysis?

A

Ester + Acid = Alcohol + Carboxylic Acid + Acid.

40
Q

What is the theoretical reaction equation for hydrolysis of an ester by a strong alkali?

A

Ester + Alkali = Alcohol + Carboxylic Acid.

41
Q

What is the actual reaction equation for hydrolysis of an ester by a strong alkali and why is this?

A

Ester + Alkali = Alcohol + Salt of the Acid

This is due to the ester being broken up into the alcohol and acid, the newly formed acid will be neutralised in the alkaline conditions to give the salt of the acid.
For example:
Ethyl Ethanoate + Alkali = Ethanol + Sodium Ethanoate
CH3CH2OOCCH3 + NAOH = CH3CH2OH + NaOOCCH

42
Q

How can the products of alkaline hydrolysis be separated?

A

We can separate the products using distillation as the alcohol will have a lower boiling point than the dissolved salt of the acid. After distillation the last step in recovering all the products is to acidify the acid salt to retrieve the the carboxylic acid. We do this by adding dilute HCL.

Sodium Ethanoate + HCL = Ethanoic Acid + NaCl (salt)
Na(+) + OOCCH + H(+) + Cl(-) = HOOCCH + NaCl
(All are aqueous)
Finally we would use distillation to separate the Ethanoic acid from the NaCl.

Z/ HIGHER Chemistry (25 decks)

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