Where do we come from?

The « lycée »Chrestien de Troyes

Time tableFrench :4 hoursMath :5 hoursHistory : 3 hoursBiology : 4 hoursChemistry and physic : 4 ½ hoursGerman : 2 hoursEnglish : 2 hoursSport : 2 hours« TPE »: to work on the project « Comenius » : 2 hoursscore : 28 ½ hours

we don't work on Wednesday afternoonsometimes we have school from 8 am to 6 pmwe have a 1hour-break for lunch at 11am or 12 am

School system

KinderGarten

3 years old

6 years old

11 years old

16 years old

6ème 5ème 4ème 3ème 2nde 1ère

TERMINALE

« Collège » « Lycée »Primary school

CP CE1 CE2 CM1 CM2

« Brevet des collèges » « BAC »EXAM :

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 SO

2 produced by the volcanoes

Example: this volcano, "Kawah Idjen" has a lake of 38 million m3 of sulphuric acid (island of Java, in Indonesia)

- Nitric oxide (NO) in exhaust fumes- Nitrogen dioxide (NO

2)

- NO2 due to the production of electricity and

weldings - Use of explosives- Industries use coal, oil or fuels rich in sulphur, they produce SO

2 which is transformed into sulphuric acid

(H2SO

4).

- Cast iron- Wood transformed into paper- Incineration of waste- Aerosols

Human causes : they represent more than 6 billion tons of gas !

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 + H

2O = HCO

3- + H+

2) Nitrogen dioxide : NO2

2 NO + O2 = 2 NO

2

3 NO2 + H

2O = 2 HNO

3 + NO

3) Sulphur dioxide : SO3

2 SO2 + O

2 = 2 SO

3

SO3 + H

2O = H

2SO

4

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 CO

2. Then we measured the pH.

For that, we put sodium hydrogenocarbonate (NaHCO

3) in a bottle with hydrochloric acid (HCl). As

a result, there was an emission of CO2.

NaHCO3

Distilled water

HCl

NaHCO3

HCl

Distilled water

CO2

After taking enough gas while leaving distilled water in the bottle, we stopped the reaction and we shook the bottle to dissolve CO

2 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 NO

2 in a

little quantity of distilled water. Then we measured the pH.

For that we put pieces of copper and nitric acid (HNO

3) in a bottle. As a consequence, NO

2 was

emitted.

Cu + HNO3

NO2

Cu + HNO3

NO2

Distilled water

After taking enough gas, we added distilled water in the bottle. We closed it and we shook to dissolve NO

2 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 NO

2 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 CO

2. But we

did not observe any precipitate : so there is not much dissolved CO

2 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 water2) 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 = 5pH at the end = 6

Those results show that no gas responsible for acid rain is present in the air above Troyes.

Consequences

Acid rain

Soil

Faun

Forests

Lakes

Health

Monuments

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 !!!!!