DJA 4). Alkanes Flashcards Preview

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Flashcards in DJA 4). Alkanes Deck (25):
1

what are alkanes

saturated hydrocarbons containing only c-c and c-h single bonds

2

general formula of alkanes

CnH2n+2

3

what is crude oil

a mixture of hydrocarbons of different sizes
not very useful and needs to be separated

4

how to separate crude oil

fractional distillation

5

how fractional distillation works

heated to vapour
fed up fractionating column
fractionating tower has a temperature gradient: hot at bottom, cool at top
as vapour rises it cools and condense at their boiling points and are separated off. longest chains at bottom, shortest at the top

6

as the carbon chains get longer, the hydrocarbons...
(viscosity, ignition, volatile, boiling point)

-become more viscous
-harder to ignite
-less volatile
-have higher boiling points

7

why crack

to break down long chain, in less demand, alkanes into short chain, more commercially useful,

8

thermal cracking conditions

700-1,200K
7,000kPa

9

thermal cracking tend to produce

short chain alkenes (and alkanes)

10

middle step of thermal cracking

free radicals form

11

catalytic cracking conditions

720K
low pressure
zeolite (honeycomb structure -large surface area, aluminosilicates)

12

catalytic cracking tends to produce...

branched alkanes, cycloalkanes, aromatic compounds

13

3 different products of combustion (complete and both types of incomplete)

CO2 + H2O colourless gas
CO + H2O toxic gas
C + H2O black solid

14

side products of the internal combustion engine and where they come from

NOx from the air
SO2 from sulfur in coal
unburnt hydrocarbons

15

equation for N2 into NO

N2 + O2 ----> 2NO

16

how SO2 turns into acid rain

SO2 + H2O ---> H2SO3
H2SO3 + H2O -----> H2SO4

17

how sulfur is prevented and chemical equation

flue gas desulphurisation, SO2 is removed by reacting the coal with CaO
SO2 + CaO + 2H2O+ 0.5O2 ---> CaSO4.2H2O

18

role of catalytic converter and what catalyst is present

remove NOx and unburnt hydrocarbons
Pt or Rh (honeycomb structure)

19

2 equations for the workings of catalytic converters

2CO + 2NO ---> 2CO2 + N2
C8H18 + 25NO ---> 8CO2 + 12.5N2 + 9H20

20

fuel gases
-temp
-carbon chain
-uses

25degrees
1-4
calor gas, LPG

21

gasoline
-temp
-carbon chain
-uses

40 degrees
4-12
petrol for cars

22

naptha
-temp
-carbon chain
-uses

110 degrees
7-14
petrochemicals

23

kerosene
-temp
-carbon chain
-uses

200 degrees
11-15
jet fuel

24

disel oil
-temp
-carbon chain
-uses

300 degrees
15-19
fuel for disel engines

25

residue
-temp
-carbon chain
-uses

350 degrees
bigger than 20
fuel oil
lubricant
wax
bitumen