products of combustion and pollutants

Question 1

normal nitrogen reactivity vs in a car engine ~ oxides of nitrogen

Answer 1

-normally nitrogen is too unreactive to react with oxygen in the air
-in a car engine, high temperatures and pressures are reached causing oxidation of nitrogen to take place

Question 2

equations for reactions of nitrogen with oxygen ~ oxides of nitrogen

Answer 2

N2(g) + O2(g) → 2NO(g)

N2(g) + 2O2(g) → 2NO2(g)

Question 3

oxides of nitrogen and VOCs ~ oxides of nitrogen

Answer 3

-oxides of nitrogen are released in the exhaust fumes into the atmosphere
-car exhaust fumes also contain unburnt hydrocarbons and fuels form their oxides (VOCs)
-in the air the nitrogen oxides can react with these VOCs to form peroxyacetyl nitrate (PAN) which is the main pollutant in photochemical smog
-PAN is also harmful to lungs, eyes and plant-life

Question 4

nitrogen oxides and rain ~ oxides of nitrogen

Answer 4

-nitrogen oxides dissolves and react in water with oxygen to form nitric acid which is a cause of acid rain
-acid rain causes corrosion of buildings, endangers plant life and aquatic life as the lakes and rivers become too acidic. as well as directly damaging human health

Question 5

what is put into car exhausts to reduce amount of amount if pollutants released from exhaust fumes ~ catalytic removal

Answer 5

catalytic converters

Question 6

precious metals in catalytic converters ~ catalytic removal

Answer 6

for example platinum are coated on a honeycomb to provide a large surface area

Question 7

what 3 reactions take place inside a catalytic converter ~ catalytic removal

Answer 7

-Oxidation of CO to CO2:
2CO + O2 → 2CO2

or

2CO + 2NO → 2CO2 + N2

-Reduction of NO to N2:
2CO + 2NO → 2CO2 + N2

-Oxidation of unburnt hydrocarbons:
CnH2n+2 + (3n+1)[O] → nCO2 + (n+1)H2O

Question 8

equation for oxidation of CO to CO2 ~ catalytic converter

Answer 8

2CO + O2 → 2CO2

or

2CO + 2NO → 2CO2 + N2

Question 9

equation for reduction of NO to N2 ~ catalytic converter

Answer 9

2CO + 2NO → 2CO2 + N2

Question 10

oxidation of unburnt hydrocarbons ~ catalytic converter

Answer 10

CnH2n+2 + (3n+1)[O] → nCO2 + (n+1)H2O

Question 11

what is the main way of reducing sulfur dioxide emissions ~ reducing SO2 emissions

Answer 11

treat waste gases form fired power stations

Question 12

how are wate gases from coal fired power stations treated ~ reducing SO2 emissions

Answer 12

wate gases are passed into a scrubbing chamber which sprays a wet slurry of calcium oxide and calcium carbonate into the gases
-this process is also known as sulfur scrubbing or flue gas desulfuristaion

Question 13

how can calcium oxide be used to treat wate gases form coal fired power stations + equation ~ reducing SO2 emissions

Answer 13

calcium oxide and water react with sulfur dioxide to initially produce calcium sulphite, which is then further oxidised to calcium sufate or gypsum
CaO (s) + 2H2O (l) + SO2 (g) + ½O2 (g) → CaSO4.2H2O (s)
-calcium carbonate can also be used
CaCO3 + ½O2 (g) + SO2 (g) → CaSO4 (s) + CO2 (g)

Question 14

equation for calcium oxide and water react with sulfur dioxide to initially produce calcium sulphite, which is then further oxidised to calcium sufate or gypsum ~ reducing SO2 emissions

Answer 14

CaO (s) + 2H2O (l) + SO2 (g) + ½O2 (g) → CaSO4.2H2O (s)

Question 15

equation for calcium carbonate and water react with sulfur dioxide to initially produce calcium sulphite, which is then further oxidised to calcium sufate or gypsum ~ reducing SO2 emissions

Answer 15

CaCO3 + ½O2 (g) + SO2 (g) → CaSO4 (s) + CO2 (g)

Question 16

how is carbon monoxide formed

Answer 16

incomplete combustion of alkanes in car engines

Question 17

environmental consequence of carbon monoxide

Answer 17

toxic gas

Question 18

equation for catalytic removal for CO

Answer 18

oxidation to CO2
2CO + O2 → 2CO2

or

2CO + 2NO → 2CO2 + N2

Question 19

how are oxides of nitrogen formed

Answer 19

oxidation of nitrogen in car engines

Question 20

oxides of nitrogen environmental consequence

Answer 20

dissolve and react in water with oxygen to form acid rain

Question 21

oxides of nitrogen catalytic removal equation

Answer 21

reduction to nitrogen gas
2CO + 2NO → 2CO2 + N2

Question 22

how are VOCs formed

Answer 22

unburnt hydrocarbons from fuels and their oxides formed in car engines

Question 23

environmental consequence of VOCs

Answer 23

react with oxides of nitrogen in the atmosphere to produce PAN

Question 24

catalytic removal of VOCs

Answer 24

-oxidise unburnt hydrocarbons to carbon dioxide and water
CnH2n+2 + (3n+1)[O] → nCO2 + (n+1)H2O

Question 25

how is PAN formed

Answer 25

from photochemical reaction of VOCs and nitrogen oxides in the atmosphere

Question 26

environmental consequence of PAN

Answer 26

photochemical smog

Question 27

catalytic removal of PAN

Answer 27

oxidise unburnt hydrocarbons and reduce nitrogen oxides to prevent formation of PAN in the atmosphere