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Organic Chemistry > Alkanes > Flashcards

Alkanes Flashcards

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1
Q

What does fractional distillation of crude oil do?

A

Separate hydrocarbons into fractions

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2
Q

What two physical processes are involved in fractional distillation

A

Boiling and condensation (as fractions leave column as liquids)

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3
Q

What is a fraction

A

A mixture of hydrocarbons with similar boiling points

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4
Q

What do C1 to C4 carbons make

A

Liquefied petroleum gas

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5
Q

What do C5 to C9 carbons make

A

Chemicals

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6
Q

What do C5 to C10 carbons make

A

Petrol for vehicles

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7
Q

What do C10 to C16 carbons make

A

Jet fuel and paraffin

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8
Q

What do C14 to C20 carbons make

A

Diesel fuels

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9
Q

What do C20 to C50 carbons make

A

Waxes, lubricants and polishes

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10
Q

What do C20 to C70 carbons make

A

Fuels for ships, factories and central heating

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11
Q

What do >C70 carbons make

A

Bitumen for roads and roofing

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12
Q

Describe fractional distillation

A

Hydrocarbons separates due to different boiling points
Boiling point depends on C Chain length
Cooler at top of column
Higher boiling point chains evaporated at the bottom of the column

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13
Q

Define saturated hydrocarbons

A

Contains single bonds ONLY

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14
Q

Define unsaturated

A

Contains at least one C=C double bond

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15
Q

Define hydrocarbon

A

Contains hydrogen and carbon only

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16
Q

Why do we crack long chain alkanes?

A

Shorter chain alkanes are in higher demand

17
Q

Give the conditions of thermal cracking

A

High temperature- 1000K
High pressure- 7000kPa
Free radical intermediates

18
Q

What does thermal cracking produce

A

High percentage of alkenes and straight chain alkanes

19
Q

Give the conditions of catalytic cracking

A

High temperature- 720K
Moderate pressure - 100-500kPa
Uses catalysts eg zeolite crystals
Carbocations intermediates

20
Q

What is catalytic cracking used to produce

A

Motor fuels
Aromatic hydrocarbons
Cycloalkanes

21
Q

What are the products of the complete combustion of alkanes

A

H20 and CO2

22
Q

Products of the incomplete combustion of hydrocarbons

A

CO and water

Or

C and water

23
Q

Why is

a) carbon monoxide
b) Carbon particulates
c) CO2

a pollutant

A

a) It is poisonous
b) exacerbates asthma
c) green house gas

24
Q 
Why are 
Nitrogen oxides
Sulphur dioxide
Water vapour 
Pollutants?
A

NO and NO2 form nitric acid with water and cause acid rain

SO2 forms H2SO4, causing acid rain

Water vapour is a greenhouse gas

25
Q

How is NO and NO2 formed

A

N2 and O2 react together when a spark is generated in a hot engine

26
Q

How is sulphur removed?

Give the equation

A

Glue gas desulphurisation:

It is neutralised by CaO or CaCO3

CaO + SO2 —> CaSO3

This prevents acid rain

27
Q

Why is CaO used in desulphurisation

A

It is a base and SO2 is acidic

28
Q

Why are catalytic converters fitted to cars

A

Reduce amount of CO, C, and NO produces

29
Q

Equation for formation of NO

A

N2 + O2 —> NO2

30
Q

Describe the catalyst used in catalytic converters

A

Honeycomb structure to increase surface area and improve cost effectiveness
Made of ceramic material to withstand high temperatures
Honeycomb is coated in catalyst (eg Platinum, palladium or rhodium)

31
Q

What happens to the pollutant gases as they pass over the catalyst in a converter?

A

They are adsorbed on the surface of the catalyst (held to the catalyst’s surface)

32
Q

What is the equation for the conversion of CO and NO in a catalytic converter

A

2CO + 2NO —> 2CO2 + N2

33
Q

What is the equation for C8H18 and NO in a catalytic converter?

A

C8H18 + 25NO —> 8CO2 + 12.5N2 +9H2O

34
Q

Conditions for catalytic cracking

What does it produce

A

High temperature
Moderate pressure
Zeolite catalyst

Branched and cyclic alkanes,
Aromatics
Motor fuels

35
Q

How is the exhaust gas octane removed

A

React with NO in a catalytic converter to produce CO2, N2 and H2O

36
Q

Reaction of octane and NO

A

C8H18 + NO —-> CO2 + N2 + H2O

Organic Chemistry (12 decks)

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