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Chemistry > Chemistry 5.3 > Flashcards

Chemistry 5.3 Flashcards

1
Q

What is the functional group of alcohols?

A

-OH

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2
Q

What are the 3 ways ethanol can undergo oxidation?

A

Combustion
Microbial oxidation
Heating with potassium dichromate (oxidising agent)/ chemical oxidation

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3
Q

What is the word equation for the combustion of ethanol?

A

ethanol + oxygen –> carbon dioxide + water

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4
Q

Describe combustion of ethanol

A

Ethanol combusts completely due to oxygen atom in -OH group.
Non-luminous, blue flame observed

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5
Q

Describe microbial oxidation

A

Bacteria uses oxygen in the air to oxidise ethanol into ethanoic acid

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6
Q

What can microbial oxidation only occur in the prescence of?

A

Can only happen aerobically, only if bacteria is in prescence of oxygen

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7
Q

What is vinegar?

A

An aqueous solution of ethanoic acid (formed during microbial oxidation of ethanol)

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8
Q

What is the word equation for microbial oxidation of ethanol?

A

Ethanol + oxygen –> ethanoic acid + water

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9
Q

What is ethanol heated with when being oxidised by an oxidising agent (chemical oxidation)?

A

Potassium dichromate (VI) solution in sulfuric acid

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10
Q

What is produced when ethanol undergoes oxidation due to an oxidising agent?

A

ethanoic acid + water

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11
Q

Chemical equation for oxidation of ethanol with potassium (IV) dichromate

A

CH3CH2OH + [O] –> CH3COOH +H2O

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12
Q

What is the colour change observed when ethanol is oxidised to produce ethanoic acid (using potassium dichromate and sulphuric acid)?

A

Orange to green

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13
Q

What is the reason for the colour change during chemical oxidation of ethanol?

A

Orange dichromate (IV) ions are turned into green chromium (III) ions

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14
Q

Molecular formula of ethanol

A

C2H6O

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15
Q

Structural formula of ethanol (one used if not specified)

A

C2H5OH or CH3CH2OH

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16
Q

What are the 2 ways ethanol is made?

A

Hydration of ethene
Fermentation of glucose

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17
Q

Describe the process of hydration of ethene to make ethanol

A

Ethene gas is mixed with steam at 300oC, 65 atm pressure. Phosphoric acid (H3PO4) is used as a catalyst.

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18
Q

Describe the process of fermentation to produce ethanol?

A

Glucose is fermented using yeast, at 30oC and under anaerobic conditions.
Mixture of ethanol and water is separated by fractional distillation at the end

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19
Q

What are the conditions needed for fermentation to produce ethanol?

A

30oC
Absence of air (anaerobic conditions)
(Yeast needed to provide enzymes)

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20
Q

Why must fermentation occur at 30oC?

A

Optimum temperature of enzymes. Too low would slow fermentation reaction, too high would denature enzymes

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21
Q

Why must fermentation occur with an absence of oxygen?

A

Allows yeast to respire anaerobically, producing ethanol. Also prevents oxidation. If this didn’t occur anaerobically, CO2 and H2O would be produced.

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22
Q

Conditions needed for hydration of ethene to produce ethanol?

A

300oC
65 atm pressure
Phosphoric acid catalyst

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23
Q

Advantages of fermentation to produce ethanol

A

Renewable raw material used (sugar cane to provide glucose)
Condition not energy-intensive

24
Q

Word equation for fermentation to produce ethanol

A

Glucose —(yeast)–> ethanol + carbon dioxide

25
Q

Disadvantages of fermentation to produce ethanol

A

Makes impure ethanol which later has to be separated by fractional distillation.
Must be done in individual batches as yeast dies off when ethanol reaches 15%

26
Q

Advantages of hydration of ethene to produce ethanol

A

Makes pure ethanol
Can run continuously (not batch process)

27
Q

Disadvantages of hydration of ethene to produce ethanol

A

Conditions require lots of energy
Non-renewable raw material used (ethene gas from crude oil)

28
Q

What is the functional group of carboxylic acids?

A

O
||
C - OH

or -COOH

29
Q

What is the display formula of ethanoic acid?

A

.. H O
| //
H - C - C
| \
H O - H

30
Q

Written formula of ethanoic acid

31
Q

What happens when carboxylic acids form salts with metals?

A

Loses H+ ion and becomes negatively charged
Turns into ___oate instead of ___oic acid

32
Q

Observations of carboxylic acids and metals

A

Effervescence - hydrogen gas is produced
Solid disappears - metal used up in reaction

33
Q

Word equation for (carboxylic) acid and metal

A

acid + metal –> salt + hydrogen

34
Q

Word equation for reaction of methanoic acid and sodium (example)

A

methanoic acid + sodium –> sodium methanoate + hydrogen

35
Q

Observations of carboxylic acids and metal carbonates

A

Effervescence - CO2 gas produced
Solid disappears - Metal carbonate used up in reaction

36
Q

Word equation for reaction of methanoic acid + sodium carbonate (example)

A

methanoic acid + sodium carbonate –> sodium methanoate + carbon dioxide + water

37
Q

Word equation for reaction of (carboxylic) acid and metal carbonate

A

Metal + acid –> salt + carbon dioxide + water

38
Q

Functional group of esters

A

. O
||
- C - O

or -COO

39
Q

How are esters formed?

A

Reaction between carboxylic acid and alcohol

40
Q

What is the name of the ester formed when ethanol and ethanoic acid react together in the prescence of an acid catalyst?

A

ethyl ethanoate

41
Q

Normal word equation for formation of an ester

A

carboxylic acid + ethanol –> ester + water

42
Q

What is the name of the acid catalyst used for ester formation?

A

Concentrated sulphuric acid (H2SO4)

43
Q

Displayed formula of ethyl ethanoate

A

.. H H O H
| | || |
H - C - C - O - C - C - H
| | |
H H H

44
Q

What kind of reaction is the formation of an ester?

A

condensation reaction (water vapour is produced)

45
Q

What are esters used for?

A

As food flavourings or in perfumes due to their distinctive smell

46
Q

Describe how to make an ester

A

Mix carboxylic acid and alcohol together
Add concentrated sulphuric acid (H2SO4) to act as a catalyst
Warm it
Tip mixture into sodium carbonate solution to neutralise the acid catalyst
Wait until fizzing stops

47
Q

Structural formula of ethyl ethanoate

A

CH3COOCH2CH3

48
Q

Properties of esters/distinctive features

A

Volatile
Fragrant/fruity smell

49
Q

What are the 2 monomers used to make a polyester?

A

Dicarboxylic acid
Diol

50
Q

What kind of reaction is making polyesters?

A

Condensation polymerisation (water is produced)

51
Q

Products when a dicarboxylic acid and a diol react together

A

Polyester and water

52
Q

Which element(s) is lost (makes water) from an alcohol when it reacts with a carboxylic acid?

A

H (hydrogen)

53
Q

Which element(s) is lost (makes water) from a carboxylic acid when it reacts with an alcohol?

A

H (hydrogen) and O (oxygen)

54
Q

How are non-biodegradable polyesters disposed of?

A

Some are recycled
Landfill
Incinerated

55
Q

Some polyesters are biodegradable, what does this mean?

A

Microbes use enzymes to break down the polymer into monomers.

56
Q

Characteristics of a homologous series

A

Same general formula
Trend in physical properties
Similar chemical reactions

57
Q

Word equation for hydration of ethene

A

ethene + water(g) –> ethanol

Chemistry (16 decks)

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