Alcohols and carboxylic acids (Section 6) Flashcards

1
Q

What is the general formula for alcohols?

A

CnH(2n+1)OH

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2
Q

What is the functional group for alcohols?

A

-OH

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3
Q

What do alcohols form when oxidised?

A

Carboxylic acids

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4
Q

Name an oxidising agent that can be used to oxidise an alcohol to form a carboxylic acid

A

Potassium dichromate(VI) (In dilute sulfuric acid)

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5
Q

State the colour change when an alcohol is oxidised

A

The potassium dichromate (VI) solution will go from orange to green

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6
Q

What is formed after ethanol is oxidised?

A

Ethanoic acid

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7
Q

What are the products of complete combustion?

A

Carbon dioxide and water

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8
Q

What are the two ways to produce ethanol?

A

Fermentation and direct hydration (Ethene and steam)

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9
Q

How is ethanol created from direct hydration (Ethene and steam)

A

.Ethene is produced from the cracking of crude oil
.Ethene (C2H4) will react with steam (H2O)to make ethanol (C2H5OH)
.The reaction needs to happen at 300 degrees C and a pressure of 60-70 atmosphere
.Phosphoric acid is used as a catalyst

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10
Q

What is the catalyst used in Direct hydration?

A

Phosphoric acid

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11
Q

What temperature should direct hydration take place at

A

300 degrees celcius

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12
Q

what pressure should direct hydration take place at?

A

60-70 atmosphere

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13
Q

What are the advantages of direct hydration?

A

.Cheap at the moment
.No waste products
.100% yeald
.Fast

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14
Q

What are the disadvantages of direct hydration?

A

.Crude oil is non renewable which means it will start to run out soon
.Ethene will eventually become expensive

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15
Q

How is ethanol created using fermentation?

A

.Sugar (glucose) is converted into ethanol using yeast
.Yeast cells contain an enzyme which is a biological catalyst
.The mixture needs to be at 30 degrees C
.If it’s too hot the enzymes denature and if it’s too cold the reaction will be too slow
.It is important to ensure the mixture is kept in anaerobic conditions otherwise the the oxygen will convert the ethanol into ethanoic acid

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16
Q

What are the advantages of fermentation?

A

.Yeast is easy to grow
.The raw materials are renewable resources
.Cheap and low energy cost

17
Q

What are the disadvantages of fermentation?

A

.The ethanol isn’t very concentrated
.Needs to be distilled and purified
.Slow

18
Q

Why does fermentation take place at 30 degrees C?

A

.30 degrees C is the optimum temperature for the enzymes in yeast cells
.If it’s too hot, they denature
.If it’s too cold, the process would be to slow

19
Q

What are the products of fermentation?

A

Ethanol and carbon dioxide

20
Q

Why is ethanol purified and distilled after fermentation?

A

As it isn’t concentrated enough after fermentation

21
Q

What is the functional group of carboxylic acids?

A

-COOH

22
Q

What is the molecular formula of methanoic acid?

A

HCOOH

23
Q

Do carboxylic contain double bonds?

A

Yes, on the carbon to the oxygen

24
Q

What are the products of Ethanoic acid + sodium carbonate?

A

Sodium ethanoate + water + carbon dioxide

25
Q

What are the products of Ethanoic acid + magnesium?

A

Magnesium ethanoate + hydrogen

26
Q

How are esters formed?

A

When an alcohol is reacted with a carboxylic acid with the presence of an acid catalyst

27
Q

How can ethanoic acid be made?

A

By oxidising ethanol

28
Q

What are the products of ethanol + oxygen?

A

Ethanoic acid + water

29
Q

How would you make vinegar?

A

.By oxidising ethanol to make ethanoic acid
.Then you can dissolve the ethanoic acid in water to make vinegar

30
Q

What is vinegar used for?

A

Flavoring and preserving foods