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Chemistry 🧪 > Alcohols and carboxylic acids > Flashcards

Alcohols and carboxylic acids Flashcards

1
Q

What are alcohols?

A

A homologous series containing -OH as the functional group.

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2
Q

How can ethanol be made?

A

Through reacting with steam or fermentation.

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3
Q

What are the conditions for the industrial preparation of ethanol?

A

300C, 60-70 atm and a catalyst of phosphoric acid.

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4
Q

What is fermentation?

A

An enzyme-catalysed reaction that converts sugars to ethanol.

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5
Q

How can ethanol be separated from the products in fermentation?

A

It can be separated from the aqueous mixture using fractional distillation as it has a boiling temperature of 80C.

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6
Q

Give an example of a fermentation reaction

A

C6H12O6 (glucose) —> 2C2H5OH + 2CO2

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7
Q

What are biofuels?

A

Fuels that have been produced using a biological source.

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8
Q

How is bioethanol obtained?

A

By the fermentation of sugars in plants and biodiesel from the oils and fats present in the seeds of some plants.

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9
Q

What are some advantages of biofuels?

A
  1. Renewable- The plants needed can be grown each year and animal waste can also be used
  2. Greenhouse gas- Although they produce CO2 when burnt, the plants have taken in CO2 for photosynthesis, making the use of biofuels carbon neutral.
  3. Economic and political security- Countries without their own source of fossil fuels are affected by change in price and availability.
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10
Q

What are some disadvantages of biofuels?

A
  1. Land use- Forests are being destroyed to create land to grow the plants for biofuels.
  2. Use of resources- Large quantities of water and fertiliser needed to grow biofuels.
  3. Carbon neutrality?- This does not take into account the fuel needed to build factories and transport of raw materials.
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11
Q

How can alcohols be dehydrated?

A

By removing water and forming a double bond, creating alkenes.

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12
Q

What are some dehydrating agents used to dehydrate alcohols?

A

Heated aluminium oxide or concentrated sulphuric acid.

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13
Q

What is a primary alcohol?

A

The OH is joined to a carbon that is joined to one other carbon.

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14
Q

What is a secondary alcohol?

A

The OH is joined to a carbon that is joined to two other carbons.

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15
Q

What is a tertiary alcohol?

A

The OH is joined to a carbon that is joined to three other carbons.

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16
Q

Describe the oxidation of primary alcohols

A

Primary alcohols -> Aldehydes -> Carboxylic acids.

17
Q

Describe the oxidation of secondary alcohols

A

Secondary alcohols -> Ketones.

18
Q

What product of oxidation has the functional group COH?

A

Aldehyde.

19
Q

What product of oxidation has the functional group COOH?

A

Carboxylic acids.

20
Q

What product of oxidation has the functional group CO?

A

Ketones.

21
Q

Why can tertiary alcohols not be oxidised?

A

As there is no hydrogen on the adjacent carbon that can be lost.

22
Q

What oxidising agent is used in the oxidation of alcohols?

A

Acidified potassium dichromate (VI).

23
Q

What test can be used for primary and secondary alcohols?

A

Add acidified potassium dichromate (VI), and a colour change from orange to green will be observed.

24
Q

What are carboxylic acids?

A

A homologous series containing COOH as the functional group. They are weak acids so only partly disassociate in an aqueous solution to form H+ ions.

25
Q

How does a carboxylic acid react with bases and alkalis?

A

Base + Acid —> Salt + Water.

26
Q

How does a carboxylic acid react with carbonates and hydrocarbons?

A

Carbonates + Acid —> Salt + Water + Carbon dioxide.

27
Q

How does a carboxylic acid react to form an ester?

A

Carboxylic acid + Alcohol —> Ester + Water.

28
Q

How is the ester made in esterification separated from the products?

A

Using distillation.

29
Q

What is the catalyst in esterification?

A

Concentrated sulphuric acid to allow the alcohol, carboxylic acid and sulphuric acid are all heated together.

30
Q

How are esters recognised?

A

They have a characteristic sweet, fruity smell and low boiling point.

31
Q

How can you identify a carboxylic acid?

A

Add sodium carbonate and CO2 bubbles are produced. This turns limewater cloudy when bubbled through it.

Chemistry 🧪 (15 decks)

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