air

Question 1

composition of unpolluted air

Answer 1

COMMON MISCONCEPTION! Hydrogen is NOT found in the natural air.
21% o2 in atmosphere
78% nitrogen
rest other gases include 0.04% co2, 0.9% argon

CANNOT do haber process on air

Question 2

uses of air

Answer 2

1. helium, argon uses
2. oxygen used, steel making, breathing apparatus, hydrogen fuel cell, combustion
3. nitrogen food packaging, produce silicon chips

Question 3

investigate percentage o2

Answer 3

1. known volume of air is passed back and forth over, hot copper powder
2. no further change in volume
3. all oxygen in the air combines, hot copper (red-brown), form copper(II) oxide (black)

Question 4

air pollutants

Answer 4

1. co2 (g)
2. CO (g)
3. particulates
4. methane
5. oxides of nitrogen
6. So2 (g)
7. unburnt hydrocarbons
8. ozone

Question 5

air pollutant
C__ d__

human source + eqn
natural source (if any)
effect

Answer 5

carbon dioxide
complete combustion, carbon containing fuels
decomposition, organic matter, bacteria

Ch4 (g) + o2 (g) -> Co2 (g) + 2H2o (g)

greenhouse gases, global warming, climate change

Question 6

air pollutant
C__ m__

human source + eqn
natural source (if any)
effect

Answer 6

carbon monoxide
incomplete combustion, carbon containing fuels, fossil fuels like octane (gasoline)

C8H18 + 9O2 -> 5CO + 2co2 + 9h2o

inhale CO,
- toxic, comb irreversibly w/ hemoglobin, carboxyhemoglobin,
- reduce o2 carry cap, blood
- less o2 transport 2 cells
- dizziness, fatigue, death

all gaseous except C8H18 (l)

Question 7

air pollutant
p___

human source + eqn
natural source (if any)
effect

Answer 7

particulates
incomplete combustion, carbon containing fuels, produce particulates, carbon (soot), e.g. fossil fuels, methane

with soot
CH4 + O2→ C + 2H2O

respiratory problems, cancer

Question 8

air pollutant
m__

human source + eqn
natural source (if any)
effect

Answer 8

methane
waste gases, digestive processes, animals
agriculture

greenhouse gases, global warming, climate change

Question 9

air pollutant
o__ o__ n__

human source + eqn
natural source (if any)
effect

Answer 9

oxides of nitrogen
vehicle engine combustion

lightning, bacterial action, soil

photochemical smog,
dissolve rain, acid rain -> corrode metal, carbonate compound struct i.e. limestone, irritate lung throat eye

Question 10

air pollutant
s__ d__

human source + eqn
natural source (if any)
effect

Answer 10

sulfur dioxide
VOLCANO
combustion, fossil fuels w/ sulfur compounds (i.e. power station)

dissolve rain, acid rain -> corrode metal, carbonate compound struct i.e. limestone, breathing difficulties

Question 11

deal w/ climate change

Answer 11

1. drastic reduce production, greenhouse gases, slow, avoid climate change
2. Co2 emissions reduced, use hydrogen/solar, other renewable source, energy, dont burn fossil fuel

Question 12

deal w/ acid rain

Answer 12

1. catalytic converters, remove oxides, nitrogen
2. decrease amt, sulfur dioxide, oxides nitrogen produce
   - use fuels, low lvls sulfur
   - flue gas desulfurisation,
   - react sulfur dioxide emitted, calcium oxide

Question 13

exhaust gases

Answer 13

oxides of nitrogen, no, no2
- nitrogen, oxygen in air react, high temp,
- internal combustion engines

others
1. unburned hydrocarbons
2. carbon monoxide

Question 14

catalytic converter characteristics

Answer 14

1. transition metal catalysts (Pt, Rhodium, Palladium, alloy)
2. redox reaction, neutralise pollutant gas
3. cars fitted, catalytic converters, exhaust system
4. make exhaust gases harmless

honeycomb struct of catalysts increase sa:vol ratio

Question 15

catalytic converter
carbon monoxide
nitrogen monoxide
nitrogen dioxide
overall

Answer 15

carbon monoxide: 2CO + O2 -> 2Co2

nitrogen monoxide: 2No -> N2 + O2

nitrogen dioxide 2No2 -> N2 + 2o2

overall: 2NO + 2CO -> N2 + 2Co2

cat converter converts all Nox to n2

Question 16

catalytic converter
unburned hydrocarbons oxidised, reduce neg effect

Answer 16

C8H18 + 12½O2 → 8CO2 + 9H2O

Question 17

is co2, ozone pollutants?

Answer 17

co2
not pollutant, found naturally at 0.04% conc., env

ozone
pollutant, harmful, human health - difficulty breathing

pollutant is anything that harms ppl at ground lvl

Question 18

pollutants
u__ h___

neg impact

Answer 18

1. liver damage
2. presence sunlight, combine w/ oxides of nitrogen, photochemical smog, brown haze
3. produce ozone, sulfur dioxide, nitrogen dioxide, air pollutants
4. respiratory problems

unburnt hydrocarbons

Question 19

which pollutant gas can be oxidised

Answer 19

carbon monoxide
unburnt petrol gases

yes these are oxidised.
rest are catalyticly converted

Question 20

pollutant gas
o__
natural source
man-made source
neg effect

Answer 20

ozone
lightning
react btwn unburnt hydrocarbons, nitrogen oxides, presence sunlight

eye, respiratory tract infection
slow down photosynthesis, plants, dmg crop

Question 21

method of flue gas desulfursation

Answer 21

wet scrubbing, CaCo3 slurry

clean gas in this context may not mean completely clean of greenhouse gases,

as co2 (g) not considered pollutant gas

Question 22

liming
definition, limitations

Answer 22

add calcium carbonate (limestone) -> soil, water bodies,
remove excess acid, acid rain

process expensive, temporary

Question 23

how does ozone layer protect us

Answer 23

• ozone filter excessive ultraviolet rays, reaching surface, earth
• skin cancer, cataracts
• kill vegetation

o3 allotrope of o2

Question 24

chloroflurocarbons
source

Answer 24

cooling system, old refridgerators
old polystryrene foam

contain chlorine, fluorine, carbon

3o2 (g) ⇌ 2o3 (g)

Question 25

CFC eqn + desc

Answer 25

1. First eqn show depletion, ozone molecules by chlorine atoms 2. second reaction show chlorine atoms regenerated, reused, destroy many o3, repeating cycle 3. **chemically unchanged, so is catalyst** ## Footnote Cl + o3 -> ClO + o2 ClO + O3 -> Cl + 2o2

Question 26

lean burn engines

Answer 26

1. higher ratio, air:fuel, less incomplete combustion, more o2 available 2. lower running temp, less N2 + o2 react form 2No2, reaction req high temp, pressure

Question 27

what burns in air, form oxide?

Answer 27

carbon, sulfur most metals

Question 28

photochemical smog reaction

Answer 28

o3 + cl -> o2 + clO

Question 29

how separate all components of air

Answer 29

fractional distillation

Question 30

which component in air lowest boiling pt

Answer 30

nitrogen ## Footnote Helium is 2nd lowest

Question 31

besides NoX and unburnt hydrocarbons -> photochem smog wat else unburnt hydrocarbons cause

Answer 31

global warming esp the main component of natural gas, methane

Question 32

before fractional distillation of air must do what

Answer 32

- cool air to liquefy it - slowly warm it up ## Footnote nitrogen low boiling pt cuz weak intermolecular FoA. nitrogen high heat req to react because strong triple covalent bond needed to be broken

Question 33

gypsum

Answer 33

hydrated calcium sulfate final production aft flue gas desulfurisation via **wet scrubbing**

Question 34

flue gas desulfurisation release co2?

Answer 34

yes

Question 35

advantage of low sulfur fuels usage over flue gas desulfurisation

Answer 35

- less costly - no space constraints - treat high sulfur fuels w/ hydrogen => H2S

Question 36

acids in acid rain

Answer 36

- sulfurous acid (So2 dissolve) - sulfuric acid (So3 dissolve) - nitric acid (no2 dissolve)

Question 37

why Cl is catalyst

Answer 37

- Cl remain chemically unchanged after reaction

Question 38

how Cl produced from CFC

Answer 38

under sunlight CFC decompose, releasing Cl atom

Question 39

when increase o2 in fuel burning, more complete combustion disadvantage

Answer 39

more complete combustion of carbon containing fuel more co2 released, greenhouse gas

Question 40

why use alloy, catalytic converter

Answer 40

stronger, harder than pure metal so last longer

Question 41

why got water in petrol engine

Answer 41

complete, incomplete combustion produce h2o (l)

Question 42

CaCo3 cannot react w/?

Answer 42

neutral gases like CO ## Footnote can react w/ co2, h2

Question 43

gypsum usages

Answer 43

drywalls, fertilisers

Question 44

disadv of bioethanol

Answer 44

- increased competition, food source - co2 is produced in production and transportation

Question 45

highest boiling pt component of air

Answer 45

oxygen