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Flashcards in Alkanes Deck (36)
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1

What does fractional distillation of crude oil do?

Separate hydrocarbons into fractions

2

What two physical processes are involved in fractional distillation

Boiling and condensation (as fractions leave column as liquids)

3

What is a fraction

A mixture of hydrocarbons with similar boiling points

4

What do C1 to C4 carbons make

Liquefied petroleum gas

5

What do C5 to C9 carbons make

Chemicals

6

What do C5 to C10 carbons make

Petrol for vehicles

7

What do C10 to C16 carbons make

Jet fuel and paraffin

8

What do C14 to C20 carbons make

Diesel fuels

9

What do C20 to C50 carbons make

Waxes, lubricants and polishes

10

What do C20 to C70 carbons make

Fuels for ships, factories and central heating

11

What do >C70 carbons make

Bitumen for roads and roofing

12

Describe fractional distillation

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

13

Define saturated hydrocarbons

Contains single bonds ONLY

14

Define unsaturated

Contains at least one C=C double bond

15

Define hydrocarbon

Contains hydrogen and carbon only

16

Why do we crack long chain alkanes?

Shorter chain alkanes are in higher demand

17

Give the conditions of thermal cracking

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

18

What does thermal cracking produce

High percentage of alkenes and straight chain alkanes

19

Give the conditions of catalytic cracking

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

20

What is catalytic cracking used to produce

Motor fuels
Aromatic hydrocarbons
Cycloalkanes

21

What are the products of the complete combustion of alkanes

H20 and CO2

22

Products of the incomplete combustion of hydrocarbons

CO and water

Or

C and water

23

Why is
a) carbon monoxide
b)Carbon particulates
c) CO2

a pollutant

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

24

Why are
Nitrogen oxides
Sulphur dioxide
Water vapour
Pollutants?

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

How is NO and NO2 formed

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

26

How is sulphur removed?

Give the equation

Glue gas desulphurisation:

It is neutralised by CaO or CaCO3

CaO + SO2 —> CaSO3

This prevents acid rain

27

Why is CaO used in desulphurisation

It is a base and SO2 is acidic

28

Why are catalytic converters fitted to cars

Reduce amount of CO, C, and NO produces

29

Equation for formation of NO

N2 + O2 —> NO2

30

Describe the catalyst used in catalytic converters

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)