Natures Chemistry Flashcards

1
Q

What are saturated compounds

A

Only contain single carbon to carbon bonds

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2
Q

What are unsaturated compounds

A

Contain atleast one carbon to carbon double bond

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3
Q

What is the test for unsaturation

A

The bromine solution test
If a molecule is unsaturated the bromine becomes decolourised

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4
Q

What is a homologous series

A

Family of compounds with similar chemical properties and a shared general formula

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5
Q

What are isomers

A

Compounds with the same molecular formula but different structural formula

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6
Q

What functional groups belongs to the alcohols (plus general formula)

A

Hydroxyl functional group = -OH
General formula = CnH2n + 1OH

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7
Q

Whats the difference between primary, secondary and tertiary alcohols

A

Primary alcohols have one carbon (2 H atoms) bonded directly to C-OH whilst secondary alcohols have two carbon atoms directly bonded to the C-OH and lastly tertiary alcohols which have three carbon atoms directly bonded to the C-OH

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8
Q

Are alcohols polar

A

Yes! Hydrogen bonding exists between the molecules

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9
Q

What is miscibility

A

How easily a liquid solute dissolves in a liquid solvent (or how well two liquid substances mix)

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10
Q

What functional group do the carboxylic acids contain ( plus general formula)

A

Carboxyl functional group = -COOH
General formula = CnH2n+1COOH

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11
Q

What products do u get when a metal oxide and a carboxylic acid react

A

Salt and water

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12
Q

What products do u get when a metal hydroxide and carboxylic acid react

A

Salt and water

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13
Q

What products do u get when a metal carbonate and carboxylic acid

A

Salt and water and carbon dioxide

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14
Q

What functional group do esters contain

A

An ester link = o-c=o

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15
Q

How do esters form

A

A condensation reaction involves two molecules joining together with the elimination of a small molecule. Im this case an alcohol and carboxylic acid (water and ester form)

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16
Q

What chemical is necessary to add when making esters

A

Concentrated sulfuric acid - acts as a catalyst and increases rate of reaction

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17
Q

In an ester forming experiment what is added to the mouth of the test tube

A

A damp paper towel to act as a condenser

18
Q

What is hydrolysis

A

When a molecule reacts with water to break down smaller molecules

19
Q

What happens when an ester is hydrolysed

A

It reacts with water in the presence of sodium hydroxide. The ester link is broken producing the parent alcohol and carboxylic acid

20
Q

Name uses of esters

A

> Used as flavourings and fragrances
Esters have pleasant, fruity smells
Used as solvents for non-polar compounds that do not dissolve in water

21
Q

How are fats and oils formed

A

Edible fats and oils are esters. Glycerol and fatty acids are the two chemicals involved in forming fats and oils

22
Q

What is the systematic name for glycerol

A

Propane-1,2,3-triol

23
Q

What are carboxylic acids known as in fats and oils

A

Fatty acids - they cam be saturated or unsaturated straight chain carboxylic acids (usually long chains)

24
Q

How are fats and oils formed

A

The condensation of glycerol and 3 fatty acids

25
Q

Explain fully why edible oils have a lower melting point than edible fats

A

Oils are more unsaturated as they contain double bonds which cause kinks in chains of fatty acids. These kinks mean the molecules cant pack closely together and results in weaker Van Der Waals forces of attraction

26
Q

Explain fully why edible fats tend to have higher melting points than edible oils

A

Fats tend to be saturated which mean their carbon chains are are long and straight. These chains can pack closely together and therefore have stronger intermolecular forces and higher mpts

27
Q

How do you distinguish between edible fats and oils

A

Use bromine solution
Unsaturated oils will quickly decolourise bromine. As the number of C-C double bonds increase so too does the volume of bromine required to decolourise it

28
Q

Why are fats and oils important for the body

A

They are a concentrated source of energy. They are essential for the transport and storage of fat-soluble vitamins in the body

29
Q

How are soaps formed

A

They are produced by the alkaline hydrolysis of edible fats and oils. This produces 3 fatty acid molecules and one glycerol molecule

30
Q

When using sodium hydroxide in alkaline hydrolysis aren the original three fatty acids formed

A

No! The fatty acids are neutralised by the alkali. Soaps are therefore fatty acid salts

31
Q

Uses of soaps

A

> used to remove non-polar substances such as oil and grease

32
Q

Describe how the structure of soaps allow them to remove non-polar substances

A

Soap ions have long non polar tails. They are hydrophobic (water-hating)
Soaps have ionic negatively charged heads that are water-soluble
They are hydrophilic (water-loving)

33
Q

Describe the cleaning action of soaps

A

Tails dissolvr in oil or gresse and heads remain in water
Agitating the water causes ball like structures to form

34
Q

How does the greese remain suspended

A

The negatively charged balls repel each other keeping it suspended

35
Q

What happens when soap is used in hard water

A

Produces an insoluble precipitate called scum
(Hard water contains high levels of dissolved metal ions)

36
Q

What solution stops scum forming in hard water

A

Soapless detergents - still have hydrophobic tails and hydrophilic heads

37
Q

What are emulsifiers used for

A

Used to prevent non polar liquids separating into layers

38
Q

How are emulsifiers similar to fats and oils

A

They are similar in the fact they have 1-2 fatty acids and a molecule of glycerol. They are made by reacting edible oils with glycerol

39
Q

How do emulsifiers differ from fats and oils

A

Whilst they form ester links with the glycerol backbone, there are still unused hydroxyl groups on the molecule

40
Q

How do emusifiers work

A

Hydroxyl groups are hydrophylic and dissolve in water, whilst fatty acid chains are hydrophobic and dissolve in oil forming a stable emulsion