Transcript www.lyceechrestiendetroyes.fr

Where
do we come from?
The « lycée »
Chrestien de Troyes
Time table
French :4 hours
Math :5 hours
History : 3 hours
Biology : 4 hours
Chemistry and physic : 4 ½ hours
German : 2 hours
English : 2 hours
Sport : 2 hours
« TPE »: to work on the project « Comenius » : 2 hours
score : 28 ½ hours
we don't work on Wednesday afternoon
sometimes we have school from 8 am to 6 pm
we have a 1hour-break for lunch at 11am or 12 am
School system
3
years
old
16 years
old
11 years
old
6 years
old
6ème 5ème 4ème 3èm 2nde
e
CP
Kinder
Garten
CE1 CE2 CM1 CM2
Primary school
EXAM :
« Collège »
« Brevet des collèges »
1ère
T
E
R
M
I
N
A
L
E
« Lycée »
« BAC »
Troyes, a town of art and history
(125,000 inhab.)
Troyes is known for its textile industry
It is famous for its factory outlets where you can
buy famous brands at good prices .
The lakes
Champagne
Normally, the rain has a
pH of 5.6.
But sometimes it can be
1.5 !
What can change the
acidity of the rain?
Natural causes :
they represent less than 0.1 billion tons of gas
- The air contains approximately 0,03% of CO2, which explains the low
acidity of rainwater (pH = 5.6)
-Forest fires
- NO2 released by the lightning
- CO2 produced by the bacteria of the ground.
- Aggravation factor : because of the wind, the clouds can move 500 km per
day.
- CO2 and SO2 produced by the volcanoes
Example: this volcano, "Kawah Idjen" has a lake of 38 million m3 of
sulphuric acid (island of Java, in Indonesia)
Human causes :
they represent more than 6 billion tons of gas !
- Nitric oxide (NO) in exhaust fumes
- Nitrogen dioxide (NO2)
- NO2 due to the production of electricity and
weldings
- Use of explosives
- Industries use coal, oil or fuels rich in sulphur, they
produce SO2 which is transformed into sulphuric acid
(H2SO4).
- Cast iron
- Wood transformed into paper
- Incineration of waste
- Aerosols
The most polluting country : the USA with more than 17 million tons of SO2
in 1996 ; 21 million tons of NO2
The least polluting countries: Sweden, Norway (both polluted by the United
Kingdom), Switzerland, Austria.
Origins of NO2 emissions in the United
Kingdom in 1998.
1,753,000 tons (NO2 and NO)
Origins of SO2 emissions in the United
Kingdom in 1998.
1,615, 000 tons
Origin of acid rain
Our experiments : description,
results and interpretation.
I. Experiments on gas potentially responsible for
acidity of the rain
1) Carbon dioxide : CO2
CO2 + H2O = HCO3- + H+
2) Nitrogen dioxide : NO2
2 NO + O2 = 2 NO2
3 NO2 + H2O = 2 HNO3 + NO
3) Sulphur dioxide : SO3
2 SO2 + O2 = 2 SO3
SO3 + H2O = H2SO4
1) Carbon dioxide
Question : Can CO2 be responsible for the high
acidity of the rain (pH=1.5)?
We carried out an experiment the purpose of which
is to saturate a small quantity of distilled water with
CO2. Then we measured the pH.
For that, we put sodium hydrogenocarbonate
(NaHCO3) in a bottle with hydrochloric acid (HCl). As
a result, there was an emission of CO2.
Distilled water
NaHCO3
HCl
CO2
HCl
NaHCO3
Distilled water
After taking enough gas while leaving distilled
water in the bottle, we stopped the reaction and we
shook the bottle to dissolve CO2 in water.
Then we measured the pH of the solution
obtained : pH = 4.
The initial pH of water was 4.6.
Thus we deduced that CO2
is not responsible for the high
acidity of the rain.
2) Nitrogen dioxide
Question : Can NO2 be responsible for the high
acidity of the rain (pH=1.5)?
We carried out an experiment the purpose of
which was to dissolve a great quantity of NO2 in a
little quantity of distilled water. Then we measured
the pH.
For that we put pieces of copper and nitric acid
(HNO3) in a bottle. As a consequence, NO2 was
emitted.
NO2
Cu + HNO3
NO2
Cu + HNO3
Distilled water
After taking enough gas, we added distilled water
in the bottle. We closed it and we shook to dissolve
NO2 in water.
Then we measured the pH of the solution
obtained : pH = 1.2. The initial pH of water was 5.1.
Thus we deduced that
NO2 could be a factor
responsible for the high
acidity of the rain.
3) Sulphur dioxide
Sulphur dioxide is very water soluble, it dissolves
in the small water droplets of the air, thanks to the
wind.
Sulphur dioxide is also responsible for the acidity
of the rain. But we did not make an experiment to
prove it.
II. Water analysis
1) Analysis of rainwater
2) Experiments on distilled water
1) Analysis of rainwater
We sampled rainwater during each downpour
(approximately 15 samples).
We measured the pH of each sample. The results
showed us that our rain is only slightly acid. Indeed
the pH is between 5.7 and 7.7.
We also measured conductivity because it varies
with the impurities.
We carried out two other tests on these water
samples.
The first one consisted in putting rainwater in a
test tube. We added lime water to detect CO2. But we
did not observe any precipitate : so there is not much
dissolved CO2 in rainwater.
The second experiment consisted in testing the
nitrates possibly present in water. But we did not find
nitrates in water, the strips did not react.
We deduced that in our area the gases responsible
for the high acidity of the rain are only very slightly
present in the air.
2) Experiments
on distilled
water
2) Experiments
on distilled
water
In order to collect gas from the air, we put a
recipient filled with distilled water outside,
protected from rain, for a week.We measured
pH at the beginning and compared it to the
end.
pH at the beginning = 5
pH at the end = 6
Those results show that no gas
responsible for acid rain is present in the air
Consequences
Faun
Soil
Lakes
Forests
Acid rain
Monuments
Health
Forest
They are more or less affected according
to their geographical site.
The forest undergo direct and indirect
consequences .
Direct consequences
In the presence of photo-oxidants, the leaves lose their waxy
coating and thus become more exposed to diseases, their color
changes .
Indirect effects
Acid rain attacks the trees indirectly and :
-weakens when damages the leaves,
-limits the elements available,
-poisons with toxic substances slowly released by the
ground.
If the ground does not manage to neutralize acidity the
trees will be the first touched .
Solutions
Limiting air pollution :
- by using cars with catalytic converter
- by using electric cars & solar power cars
- by equipping the chimneys of the
factories with purifiers to limit the
emission of nitrogen
Moreover,each one of us can also do
something to reduce the development of
the acid rains.
At home:
-reducing water consumption
-buying electric appliances which consume little
energy
-using less heating in winter
-using less air-conditioning in summer.
Transport:
-riding bikes or walking as often as possible
-using a less polluting gasoline.
Conclusion
A lot of countries try to reduce their
gas emission
because they feel
concerned by the acid rain problem ;
for several countries progress is
considerable what lets us think that
the increase of acid rain can be
slowed down, even stopped !!!!!