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Chemistry Paper 2 > C9&10 Crude oil and fuels/Organic reactions > Flashcards

C9&10 Crude oil and fuels/Organic reactions Flashcards

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1
Q

What is meant by ‘homologous series’?

A

A group of organic compounds that have similar chemical properties, due to them having the same functional group.

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2
Q

What is a ‘functional group’?

A

An atom or group of atoms that give organic compounds their characteristic reactions

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3
Q

What is the functional group in alkenes?

A

The carbon-carbon double bond.

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4
Q

What is the relative formula mass of butene?

A

C4H4 = 56

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5
Q

What type of compound is produced when an alkene is reacted with steam in the presence of a catalyst?

A

Alcohol

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6
Q

What is the functional group of alcohols?

A

-OH

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7
Q

What is the general formula for alcohols?

A

C(n)H(2n+1)OH

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8
Q

Uses of alcohols

A
  • Fuels, release energy when burnt
  • Solvents, dissolve most things that water can, plus more e.g. hydrocarbons and oils
  • Antibacterial gels, the alcohol makes it evaporate quickly
  • Drinks
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9
Q

What is a hydrocarbon?

A

A compound containing only hydrogen and carbon

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10
Q

What are alkanes?

A

Saturated hydrocarbons

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11
Q

What is the general formula of alkanes?

A

C(n)H(2n+2)

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12
Q

Describe the two types of combustion of hydrocarbons.

A

COMPLETE COMBUSTION - produces carbon dioxide and water, carbon and hydrogen atoms are completely oxidised
INCOMPLETE COMBUSTION - produces carbon or carbon monoxide and water

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13
Q

Name the first four alcohols

A

Methanol, Ethanol, Propanol and Butanol

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14
Q

Describe the two ways to produce ethanol

A
  1. Hydration - Ethene (from cracking) + steam (high temperatures + catalyst) —> Ethanol
  2. Fermentation - Sugar (from sugar cane) + yeast (room temperature, in a slightly acidic solution + a few days) —> Ethanol (+carbon dioxide)
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15
Q

Evaluate the two different ways to produce ethanol

A
  • Hydration requires high temperatures, which requires energy and money. Whereas, fermentation can be carried out at room temperature.
  • Hydration has 100% atom economy because the only product is ethanol. Whereas, fermentation produces carbon dioxide.
  • Ethene for hydration is coming from crude oil, which is a non-renewable resource. Whereas, fermentation uses sugar cane which is renewable.
  • Ethanol from sugar cane is a batch process, meaning that it is moved from one place to another. Whereas, ethanol from hydration is a continuous process.
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16
Q

Properties of alcohols

A
  • Soluble in water
  • Neutral pH
  • Highly flammable; burn with a clean flame
  • React with sodium metal to produce hydrogen gas and a metal salt
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17
Q

What does the oxidation of alcohols produce?

A

Carboxylic acids

18
Q

How are alcohols oxidised?

A
  • When exposed to oxygen
  • Or done chemically using an oxidising agent
19
Q

What are carboxylic acids?

A
  • A homologous series of compounds with the relative formula C(n)H(2n+1)COOH
  • They have the functional group COOH
20
Q

Properties of carboxylic acids

A
  • Soluble in water
  • Acidic pH (weak acid), turns orange in universal indicator
  • React with carbonates to produce carbon dioxide, water and a metal salt
21
Q

General equation for a reaction between carboxylic acid and carbonate

A

carboxylic acid + metal carbonate –> salt + carbon dioxide + water

22
Q

Carboxylic acids are weak acids - what does that mean?

A
  • They do not fully ionise in water - only some of the acid molecules dissociate, to release H+ ions, when dissolved in water.
  • They have a lower concentration of H+ than a strong acid
23
Q

General equation for the reaction between carboxylic acids and alcohols

A

carboxylic acid + alcohol —-> (acid catalyst) Ester + water

24
Q

What is produced when carboxylic acids react with alcohols?

A

Ester and water

25
Q

What are esters?

A

A homologous series of compounds with the functional group COO.

26
Q

What type of reaction undergoes to form esters?

A

A condensation reaction (between a carboxylic acid and an alcohol)

27
Q

Uses of esters

A
  • Food flavourings
  • Perfumes
28
Q

Properties of esters

A
  • Volatile, this means they have low boiling points and vaporise easily
  • Have distinctive smells and tastes
29
Q

Explain what happens when carboxylic acids dissolve in water

A
  • When they dissolve, they ionise and release H+ ions resulting in an acidic solution
  • They don’t ionise completely (not all acid molecules release their H+ ions)
  • They form weak acidic solutions
  • This means that they have a higher pH than aqueous solutions of strong acids with the same concentration
30
Q

Properties of hydrocarbons

A

As the chain length (number of carbon atoms) increases
- the boiling and melting point increases
- the volatility decreases
- the viscosity increases
- the flammability decreases

31
Q

What is the volatility of a substance?

A

The tendency to turn into a gas

32
Q

What is the viscosity of a substance?

A

How easily it flows

33
Q

What is the flammability of a substance?

A

How easily it burns

34
Q

How is the volatility of a hydrocarbon affected by its size?

A

Volatility decreases as chain length increases: short chains have a higher volatility than long chains

35
Q

How is the viscosity of a hydrocarbon affected by its size?

A

Viscosity increases as chain length increases: short chains are less viscous (very runny) than long chains (thick)

36
Q

How is the flammability of a hydrocarbon affected by its size?

A

Flammability decreases as chain length increases: short chains have a higher flammability than long chains

37
Q

How is the boiling point of hydrocarbons affected by its size?

A

Boiling point increases as chain length increases: short chains have a lower boiling point than long chains

38
Q

Explain the process of fractional distillation

A
  • Crude oil is heated and fed in near the bottom of a tall fractionating column as hot vapour
  • Temperature decreases going up the column, so as the gases move up the column the hydrocarbons condense when they reach the temperature of their boiling points
  • The different fractions are collected as liquids at different levels
  • Short-chained hydrocarbons are piped out the top of the column as gases
39
Q

Why do short-chained hydrocarbons make better fuels?

A

They ignite more easily and burn well, with cleaner flames

40
Q

What type of process/reaction is the cracking of hydrocarbons?

A

Thermal decomposition

Chemistry Paper 2 (9 decks)

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