Topic 6B Flashcards
1
Q
general formula for alkanes
A
CnH2n+2
2
Q
cracking
A
conversion of large hydrocarbons to smaller molecules by breakage of C-C bonds
3
Q
fractional distillation
A
- oil is pre-heated then passed into a column
- fractions condense at different heights
- temperature of column decreases as you go up
- separation depends on boiling point
- small molecules condense at top (low temp) and large molecules condense at bottom (high temp)
4
Q
economic reasons for catalytic cracking
A
- shorter C chains are more in demand than larger fractions
- large hydrocarbons are cracked to produce shorter ones
- the products are more useful and valuable
5
Q
reforming
A
turning straight chain alkanes into branched and cyclic alkanes and aromatic hydrocarbons
6
Q
complete combustion products
A
- CO2 and H2O
7
Q
incomplete combustion products
A
- carbon monoxide
- carbon
8
Q
cons of carbon monoxide production
A
- highly toxic
- can form a strong bond with haemoglobin in RBC
- prevents oxygen attaching to the haemoglobin as the bond is stronger between the CO and haemoglobin
9
Q
cons of carbon
A
- soot particles can cause global dimming
10
Q
where are nitrogen oxides formed
A
- nitrogen oxides form in the reaction between N2 and O2 inside the car engine
11
Q
how are nitrogen oxides formed
A
- the high temperature and spark in the engine provide sufficient energy to break a strong N2 bond
12
Q
cons of nitrogen oxides
A
- NO is toxic and can form smog
- NO2 is toxic and acidic and forms acid rain
13
Q
cons of unburn hydrocarbons
A
contribute towards formation of smog
14
Q
catalytic converters
A
remove CO, NOx and unburned hydrocarbons from the exhaust gases and turn them into harmless CO2, N2 & H2O
15
Q
what do catalytic converted have
A
- they have a ceramic honeycomb coated with a thin layer of catalyst metals, platinum, palladium, rhodium to give a large surface area
