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Higher Chemistry Unit 2; Natures Chemistry > Carboxylic acids, esters & fats/oils > Flashcards

Carboxylic acids, esters & fats/oils Flashcards

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1
Q

How can carboxylic acids be identified?

A

the presence of the carboxyl group (-COOH) and the -oic ending.

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2
Q

What can carboxylic acids react with bases e.g. alkalis to form (neutralisation)?

A

salts e.g. sodium ethanoate

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3
Q

What can carboxylic acids be reduced to ?

A

aldehydes and alcohols

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4
Q

What does a reduction reaction involve?

A

a gain of hydrogen or loss of oxygen which results in a decrease in the oxygen to hydrogen ratio

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5
Q

What are esters made by?

A

a condensation reaction

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6
Q

What is a condensation reaction?

A

where 2 small molecules join together to make a larger and water

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7
Q

What is the reaction which produces esters?

A

esterification

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8
Q

What is the equation for the formation of an ester?

A

alcohol+ carboxylic acid > ester + water

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9
Q

What do all esters contain?

A

the ester link

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10
Q

What is the reverse reaction of condensation?

A

hydrolysis

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11
Q

What are esters (naming)?

A

alkyl alkanoates

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12
Q

What are the properties of esters?

A

Esters are immiscible with water (because water is polar whereas esters are non-polar).
Esters are sweet-smelling and volatile (low boiling point)

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13
Q

What are the uses of esters?

A

flavourings for food
perfumes
solvents for non-polar substances

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14
Q

Describe the experimental set up for making esters?

A

Hot water bath (used as contents are flammable)
test tube containing alcohol and acid + conc sulphuric acid as a catalyst.
wet paper towel as a condenser (reflux (reflow) cuts down evaporation)
cotton wool
sodium hydrogen carbonate solution (neutralises acids & stops the reaction. Separates ester (oily layer)

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15
Q

What does the equilibrium mixture contain?

A

carboxylic acid/ alcohol/ ester/ water

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16
Q

What are fats and oils?

A

esters

17
Q

What is the alcohol in fats/oils?

A

glycerol

18
Q

What is the systematic name for glycerol?

A

propan-1,2,3-triol

19
Q

What does glycerol have?

A

3 hydroxyl groups

20
Q

Glycerol has 3 hydroxyl groups but what does this mean for fats/oils?

A

3 ester links

21
Q

What is the ratio to form one fat/oil?

A

1 glycerol : 3 fatty acid molecules

22
Q

What is a fatty acid?

A

very long hydrocarbon chain with a carboxyl group

23
Q

What is the reaction called when glycerol + fatty acids > lipids?

A

condensation

24
Q

What is the reaction called when fats> glycerol +fatty acids?

A

hydrolysis

25
Q

What are fats/oils also called?

A

triglycerides

lipids

26
Q

What are all fats and oils (saturated or unsaturated) classified as?

A 
Animal
Vegetable 
Marine (fish oils)
high energy foods 
provide essential fatty acids
contain some vitamins (dissolved in the fats/oils)
27
Q

What are the 2 groups fatty acids are divided into?

A

saturated fatty acids (e.g stearic acid (C17H35COOH) found in animal fats)
Unsaturated fatty acids (e.g. oleic acid (C17H33COOH) found in vegetable oils)

28
Q

What do unsaturated have that allows them decolourise bromine water?

A

C=C

29
Q

What are the differences between fats and oils?

A

Fats are solids whereas oils are liquid.

Solid fats have saturated chains whereas liquid oils have unsaturated chains.

30
Q

Why do saturated fats and unsaturated oils have different melting points?

A

The saturated, regularly shaped fat molecules pack closely and have lots of London dispersion forces between them > higher m.pt.
Unsaturated oil molecules have irregular shapes (caused by C=C). They pack loosely and have fewer London dispersion forces > lower m.pt.

31
Q

How can oil become fats?

A

By hydrogenation/ adding hydrogen

32
Q

When oils harden and become fats what happens?

A

they become saturated and m.pt is raised. margarine is an example of this

33
Q

When oils are hardened what are the fats formed called?

A

hydrogenated fats

34
Q

What does too much saturated fats/ animal in our diet cause?

A

heart disease

Higher Chemistry Unit 2; Natures Chemistry (5 decks)

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