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AQA A Level Chemistry > Organic Chapter 3: Alkenes & Alcohols > Flashcards

Organic Chapter 3: Alkenes & Alcohols Flashcards

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1
Q

What is an alkene?

A

An unsaturated hydrocarbon, represented by the formula CnH2n
Always have at least 1 C=C double bond.

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2
Q

How can you test for alkenes?

A

Add bromine water; it will go colourless if an alkene is present

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3
Q

What reactions do alkenes undergo?

A

Electrophilic addition

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4
Q

What is the order of stability between carbocations?

A

Primary is least stable
Tertiary is most stable

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5
Q

What is a primary carbocation?

A

A carbocation where there is 1 R group attached to a carbon.

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6
Q

What is a secondary carbocation?

A

A carbocation where there are 2 R groups attached to a carbon

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7
Q

What is a tertiary carbocation?

A

A carbocation where there are 3 R groups attached to a carbon

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8
Q

Why are there multiple possible products when you add hydrogen halides to unsymmetrical alkenes?

A

Different carbocation intermediates can form

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9
Q

What are polymers made from?

A

A long string of monomers

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10
Q

How do the IMFs of polymers affect their properties?

A

Long, straight chaned polymers tend to be strong & rigid
Short & branched chains tend to be weaker & more flexible

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11
Q

Why would you plasticise a polymer?

A

To make it more flexible

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12
Q

How can you find the repeating unit monomer from a polymer?

A

Remove the C=C double bond & draw the groups vertically around it (repeating unit should only be 2 carbons long)

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13
Q

What is an Alcohol?

A

A chemical that has the hydroxyl group, -OH.
Represented by the formula CnH2n+1OH

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14
Q

What is a Primary alcohol?

A

An alcohol where there is 1 R group on the Carbon attached to the OH.
Secondary = 2 R groups
Tertiary = 3 R groups

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15
Q

What do alcohols form when dehydrated?

A

Alkenes

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16
Q

What are the three stages of distillation?

A

Distilation
Separation
Purification

17
Q

What happens in the distillation stage of distillation?

A

The mixture will be acidified & heated gently with anti-bumping granules in it.
The chemicals with lower boiling points will evaporate, rise up, and then be collected in a flask, from the condenser.

18
Q

What happens in the separation stage of distillation?

A

The product from distillation will be poured into a separating funnel & mixed with water. This will dissolve all the water-soluble impurities & create an aqueous solution, which will then form as a layer.
Drain the aqeous lower layer, leaving the impure product.

19
Q

What happens in the purification stage of distillation?

A

Drain the impure product from separation into a round-bottomed flask.
Add a drying agent (such as anhydrous CaCl2) and let the mixture dry for aorund 20 minutes.
Distill the mixture formed one last time to get a pure product.

20
Q

How are alcohols produced?

A

Hydration of alkenes
Fermentation

21
Q

How does fermentation of alcohols work?

A

C6H12O6 -> 2(C2H5OH) + 2(CO2)
Reaction is carried out by yeast under anaerobic conditions
Enzyme produced by yeast works the best at 30-40 degrees
Cheap equipment & renewable resources used

22
Q

What are some advantages of biofuels?

A
  • Renewable
  • Carbon neutral due to plants
23
Q

What are some disadvantages of biofuels?

A
  • Car engines & other tech needs to be changed to use them
  • Land used to grow fuel crops can’t be used for food
  • Not entirely carbon neutral; need to be transported
24
Q

How does hydration of alkenes compare to fermentation?

A

300 degrees celcius & 60atm pressure - high cost
Faster

25
Q

What are primary alcohols oxidised to form?

A

Aldehydes & then carboxylic acids on further oxidation

26
Q

What are secondary alcohols oxidised to form?

A

Ketones

27
Q

What are Tertiary alcohols oxidised to form?

A

They cannot undergo further oxidation

28
Q

How can you tell aldehydes & ketones apart?

A

Tollen’s reagent will form a silver mirror when warmed with a ketone

AQA A Level Chemistry (25 decks)

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