B.Sc. (H) Chemistry

Description

• cours - matière potentielle : contents
• expression écrite - matière potentielle : skills
• cours - matière potentielle : structure year
• exposé
• expression écrite - matière potentielle : technical report
• expression écrite - matière potentielle : study
• expression écrite - matière potentielle : as thinking
• expression écrite

B.Sc. (H) Chemistry THREE-YEAR FULL-TIME PROGRAMME (Six-Semester Course) COURSE CONTENTS (Effective from the Academic Year 2010-2011) UNIVERSITY OF DELHI DELHI – 110 007

• chemistry of alkanes
• titrimetric analysis
• alkynes by elimination reactions
• alkylation of terminal alkynes
• university of delhi delhi
• introduction to types of organic reactions
• organic compounds
• equation of a straight line
• equation of the straight line
• equation for a straight line
• change
• paper

Sujets

• Content
• Skill
• Exposé
• Technical report
• Pauley

Informations

• Publié par: orzi
• Nombre de lectures: 16
• Langue: English

Extrait

What is theWhat is the
Ozone Hole?! Ozone Hole?!
By Hayanon
Translated by Y. Noda and Y. Kamide
Supervised by K. Takahashi

_>`‡ƒ„>f‡‘’—>„>
m˜Œƒ>j—ƒ>pƒ‘ƒ†
About 90% of the Earth‛s ozone is found
in the stratosphere. Let‛s see briefly the
history of stratospheric ozone: Who
discovered it, and how?
Sunlight is made up of different
electromagnetic waves, ranging from
short wavelength ultraviolet to long
wavelength infrared. Do you think this is
a difficult subject? Imagine a rainbow or
When a beam of sunlight passes through a prism, a prism. You see different colors in a
the rays of different wavelengths come out.rainbow, and that indicates that sunlight
contains various light waves.
In 1881, an Irish chemist W. N. Hartley Hartley asked why ultraviolet rays are not
found that ozone absorbs ultraviolet at detected in sunlight at the Earth‛s
wavelengths from 200 to 300 surface, although they exist just after
nanometers . Fifteen years later W. being radiated from the Sun. He
Huggins, an English astronomer, studied suggested that there was a large quantity
the spectra of the dog star Sirius and of ozone up in the sky that absorbs
discovered ozone absorption of ultraviolet ultraviolet radiation. An experiment with
at wavelengths from 300 to 340 a balloon was carried out to confirm his
nanometers. idea, but the balloon did not get as high as
the ozone layer.
A nanometer is one billionth of a meter.
Finally in the 1940s, rocket observations
showed the existence of stratospheric
ozone. Unfortunately, Hartley had
already passed away by then. Various
research projects started following the
finding to understand the ozone
Stratospheric distribution, its birthplace, etc. Ozone
Ozone Layer Ozone
observations began in Antarctica in 1957
as part of the International Geophysical
Year. At that time, no one could predict
that these observations would lead to the
discovery of the ozone hole.
As research has progressed, people began Ozone Tropospheric
increases Ozone to acknowledge that animal and plant life
from pollution
is protected by the ozone layer that
absorbs harmful ultraviolet. Behind
today‛s research lie the accomplishments
Ozone concentration of scientists like Hartley, who first
studied the chemical, ozone.The ozone layer lies about 15 - 40 km in altitude,
although this height varies with latitude.
We hope you readers share an adventure <Courtesy of WMO Report “Scientific
Assessment of Ozone Depletion 2002”> trip into ozone with our Mol and Mirubo!
O3
Altitude (kilometers)Here are science lover
Mol and her robotic
dog Mirubo ... glancing at drifting
clouds, lying on their
backs in the meadow
on a nice and warm day.
Mirubo, The skywhat do you
think there is should beabove the
Above theclouds? up there.clouds?
Hmm...
1Boo-
boo
Don't you
She is at a Of course I havehave the I expect you
rebellious imagination.slightest to tell me
It would be nice ifimagination? age.
something there was a huge
interesting. food court over
the clouds.
Wait! high above the
I remember ...
clouds is
the ozone layer.
I heard
that
before.
The ozone
layer?
What is
that?
2Breeeathe!
Wow!!
Sensei, would Now,
you explain how much doMol and
to us what you know aboutSure! Mirubo, ...
ozone is? ozone?It's my
field.
Uhmm
......??
How about Oh, I know
oxygen, a lot.
then?
I take in
a vast amount
of oxygen
everyday.
It consists Ozone
of oxygenexists high
atoms.above us ...
3The area whereWhen an oxygen
ozone moleculesmolecule (O )2
concentrate isis struck by
called ... ultraviolet rays, ... the
ozone layer!
it splits
into two
oxygen
atoms.
Then, a single
The ozone layeroxygen atom
absorbs much ofcombines with Just like a
the ultravioletanother oxygen shield, the
radiation which ismolecule. ozone layer
harmful to life.
protects the
Earth.Three oxygen
atoms finally
form an ozone
molecule (O ).3
Without
there would be
the ozone
no life on the
layer, ...
Earth.
4Hip, hip,
hurray!
Calm down.Waaahhh!
We have the Let me remindUltraviolet
ozone layer you that thereradiation is Whaaaat?!
protecting us. is a worry.dangerous!
No need to
worry.
In the 1980s,
More ultraviolet
scientists found
radiation is That isthat ozone was
coming through
being lost over a crisis!!the hole??It looks likeAntarctica.
there is a
Wait.hole
in the ozone
layer.
The ozone hole
exists over
We are safe,Antarctica, not
anyway.Japan.Antarctica
WWhat ahat a
rrelief!elief!
Don‛t tell
No!! Penguins me you are
will get serious.
sunburned!
5In fact, a similarWe can‛t say It is an importantphenomenon iswe are safe from Its influence issue for theobserved overthe ozone hole reaches us people living inthe Arctic.over Antarctica. no matter the area.
how far it is.
What
stands forpunches the CFCs, chlorofluoro-holes in the
And how??
ozone layer?? carbons, these
make the holes.
Until some ten
years ago, CFCs were
air conditioners,
widely used for ...
refrigerators,
spray cans, etc.
6