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Chemistry > 7. Organic chemistry (alkenes, combustion of alkenes) > Flashcards

7. Organic chemistry (alkenes, combustion of alkenes) Flashcards

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1
Q

What is an alkene?

A

An unsaturated hydrocarbon with the general formula CnH2n

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2
Q

What do alkenes contain?

A

C = C (double bonded carbons)

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3
Q

What is the bromine test for alkenes?

A
  • Add bromine water to an alkene
  • If alkene is present there is a colour change from orange to colourless
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4
Q

Why are alkenes very reactive?

A

they are very unstable, due to the carbon-carbon double bonds, so the carbons will react with anything to go back to its stable form

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5
Q

Describe the combustion of alkenes?

A

alkenes burn with a smoky flame due to incomplete combustion

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6
Q

What are the 3 addition reactions for alkenes?

A
  1. Hydrogenation
  2. Hydration
  3. Halogenation
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7
Q

What is hydrogenation?

A

reacting an alkene with hydrogen gas to produce an alkane

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8
Q

What is the process of hydrogenation?

A
  1. React alkene with hydrogen
  2. With high temperatures (150 degrees Celsius) and a Nickel catalyst
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9
Q

What is hydration?

A

reacting an alkene with water to produce an alcohol

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10
Q

What is an alcohol?

A

An organic compound that contains an -OH functional group

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11
Q

What is the process of hydration?

A
  1. React an alkene with steam
  2. High temperatures, high pressure and acid catalyst (phosphoric acid)
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12
Q

What is halogenation?

A

reacting an alkene with a halogen to produce a haloalkane

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13
Q

What is the process of halogenation?

A
  1. An alkene is reacted with a halogen
  2. Reaction readily occurs at room temperature
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14
Q

State the characteristics of methanol, ethanol, propanol and butanol

A
  • dissolve in water to form a neutral solution
  • react with sodium to form hydrogen
  • burn in oxygen
  • react with carboxylic acids in presence of acid catalysts to form esters
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15
Q

What are 3 uses of alcohols?

A
  • fuels
  • as a solvent in industry
  • drinks
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16
Q

What are the properties of alcohols?

A
  • they can be oxidised to carboxylic acids
  • they are flammable
  • they are soluble
  • they have a pH of 7
17
Q

State the conditions required for the fermentation of glucose

A
  • 30 degrees celsius
  • aqueous solution of the glucose
  • absence of air
  • yeast added
18
Q

State the chemical equation for a fermentation reaction?

A

C6H12O6 (glucose) → 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide)

19
Q

What are carboxylic acids?

A

Organic compounds that contain a -COOH functional group

20
Q

State the characteristics of carboxylic acids

A
  • dissolve in water to form an acidic solution
  • react with metal carbonates to form carbon dioxide
  • react with alcohols with an acid catalyst to form esters
  • react with metals to give off hydrogen gas
21
Q

What type of acid is carboxylic acid?

A

a weak acid

22
Q

Explain why carboxylic acids are weak acid?

A
  • They are partially dissociated in water
  • thus the pH of a carboxylic acid in solution is not as low as the pH of a solution of a strong acid of the same concentration
23
Q

What is an ester?

A

An organic compound with a -COO- functional group

24
Q

How is an ester formed?

A

from carboxylic acid and alcohol in the presence of a sulfuric acid catalyst

25
Q

What kind of smell does an ester have?

A

a fruity or sweet smell

26
Q

What is the test to distinguish between alkanes and alkenes?

A

bromine water test

27
Q

What is the general formula for carboxylic acids?

A

CnH2n+1COOH

28
Q

How can multiple alkenes form polymers when reacted together?

A

multiple alkenes can break the double bond when reacting and form new carbon-carbon bonds forming polymers

29
Q

What is the general formula for alcohols?

A

CnH2n+1OH

30
Q

Is ethene a renewable or non-renewable resource?

A

non-renewable as it is made from crude oil

31
Q

Ethanoic acid + ethanol produces…?

A

ethyl ethanoate

32
Q

What is a functional group?

A

that part of the compound that reacts

33
Q

What are the first 4 members of the homologous series of alkenes?

A
  • ethene
  • propene
  • butene
  • pentene
34
Q

Why are alkenes unsaturated?

A

alkenes have carbon-carbon double bonds (C=C) which means they have fewer hydrogens than their corresponding alkanes

Chemistry (34 decks)

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