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HIGHER CHEMISTRY > 2d) - Esters Fats And Oils > Flashcards

2d) - Esters Fats And Oils Flashcards

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1
Q

What is an ester

A

An ester is a molecule containing an ester link - COO -

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2
Q

What happens in a condensation reaction

A

In a condensation reaction, two molecules are joined together with the elimination of a small molecule

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3
Q

Which reaction are esters formed by?

A

Esters are formed by a condensation reaction between an alcohol and a carboxylic acid with concentrated sulphuric acid as a catalyst

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4
Q

Which catalyst is used in the esters experiment

A

Concentrated sulphuric acid

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5
Q

What is the equation for an ester

A

Alcohol + carboxylic acid ——> ester + water

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6
Q

How to name an ester

A
  • first part comes from the parent alcohol
  • second part comes from the parent carboxylic acid
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7
Q

What is the small molecule eliminated when an ester link is formed

A

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

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8
Q

What happens in a hydrolysis reaction

A

In a hydrolysis reaction, a molecule reacts with water to break down into smaller molecules

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9
Q

What is produced when esters are hydrolysed

A

Esters can be hydrolysed to produce an alcohol and a carboxylic acid

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10
Q

What is the equation for breaking down (hydrolysis) of an ester

A

Ester + water ——> acid + alcohol
<——

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11
Q

What can esters be 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

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12
Q

What is the equipment required for the making esters experiment

A
  • beaker x2
  • test tube
  • paper towel
  • elastic band
  • concentrated sulphuric acid
  • sodium hydrogen carbonate
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13
Q

How do we know an ester has formed

A

Ester makes oily/solid layer

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14
Q

Why is a wet paper towel with elastic band used

A

Acts as a condenser

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15
Q

Why can we not use a Bunsen burner in the esters experiment

A

Alcohol is flammable so we don’t use a Bunsen burner

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16
Q

Which temperature can water boil to

A

Water only boils to 100 degrees celcius

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17
Q

What is the role of fats and oils

A

Fats and oils are an essential part of the diet. They provide the body with energy

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18
Q

What type of source of energy are fats and oils

A

Fats and oils are a more concentrated source of energy than carbohydrates

19
Q

How are edible fats and oils formed

A

Edible fats and edible oils are esters formed from the condensation of glycerol and three carboxylic acid molecules

20
Q

What is glycerol

A

Glycerol is a trihydric alcohol it has three alcohol groups the correct name is propan 1,2,3 triol

21
Q

What are the carboxylic acids in fats and oils known as

A

The carboxylic acids are known as ‘fatty acids’ and can be saturated or unsaturated straight - chain carboxylic acids, usually with long chains of carbon atoms

22
Q

Draw the structure of glycerol

A

Check jotter for answer

23
Q

Draw the structure of the fatty acids

A

Check jotter.

24
Q

What is the mole ratio of fatty acids to glycerol in fats and oils

A

Fats and oils are formed by the combination of 3 moles of fatty acids to 1 mole of glycerol - a triglyceride

25
Q

How many ester linkages are in one fat/oil

A

There are 3 ester linkages in the one molecule

26
Q

Which of edible fats and oils have a lower melting point

A

Edible oils have a lower melting point than edible fats

27
Q

Draw an equation showing the condensation of glycerol and three fatty acids also showing what is produced

A

Check jotter for answer

28
Q

What do double binds in fatty acid chains prevent

A

Double bonds in fatty acid chains prevent oil molecules from packing closely together.

29
Q

What does a greater number of double bonds present mean

A

The greater the number of double bonds present, the weaker the Van der waals (LDF) forces

30
Q

What is the trend between the degree of unsaturation and melting point

A

The greater the degree of unsaturation , the lower the melting point

31
Q

How many LDFs do fats have

A

Fats have higher melting points so more LDF

32
Q

How many LDFs do oils have

A

Oil - lower melting point so less LDFs

33
Q

What is the relationship between double bonds and melting points

A

Double bonds in fatty acids chains prevent oil molecules form packing closely together, so the greater the number of double bonds present the weaker the Van der waals (LDF) forces of attraction. The greater the degree of unsaturation the lower the melting point

34
Q

What do unsaturated compounds decolourise quickly

A

Unsaturated compounds quickly decolourise bromine solution

35
Q

What do the bromine molecules do to the double bonds in an addition reaction

A

The bromine molecules add across the carbon - carbon double bonds in an addition reaction

36
Q

What does the greater the number of double bonds present in a substance indicate

A

The greater the number of double bonds present in a substance, the more bromine solution can be decolourised

37
Q

Fats and oils are :

A
  • a concentrated source of energy
  • essential for the transport and storage of fat -soluble vitamins in the body
38
Q

What state are fats at room temp

A

Fats are solids at room temperature

39
Q

Why are fats solid at room temperature

A

Because they have a linear arrangement and can pack closely together it means their London dispersion forces are stronger between the molecules. Because they cab get closer together their interactions are stronger which gives them a higher melting point

40
Q

What state are oils at room temperature

A

Liquid

41
Q

Why are oils liquid at room temperature

A

Due to the double bonds in oils it is much more difficult to get the molecules to pack closely together which means the London dispersion forces between the molecules are weaker because they can’t interact as strongly which means the melting point will be lower

42
Q

How can you increase the melting point of an oil

A

We can increase the melting point of an oil by hardening the oil. This is done by hydrogenation where you add hyrdrogen to the double bond breaking apart the double bond making it more saturated which in turn increases the melting point

43
Q

Can an alkali being added in a reaction produce an ester

A

No alkalis break up esters

HIGHER CHEMISTRY (21 decks)

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