Environment Atmosphere ~ Chapter 20 ~

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Definitions

Air-The invisible gaseous substance surrounding the earth, a mixture mainly of oxygen and nitrogen.

Liquid Air – Air in its liquid state, intensely cold and bluish, obtained by cooling and compression.

Acid rain-Rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm, typically to forests and lakes. The main cause is the industrial

burning of coal and other fossil fuels, the waste gases from which contain sulfur and nitrogen oxides, which combine with atmospheric water to form acids

Ozone Layer-A layer in the earth's stratosphere at an altitude of about 10 km (6.2 miles) containing a high concentration of ozone, which absorbs most of the

ultraviolet radiation reaching the earth from the sun.

Allotrope-Each of two or more different physical forms in which an element can exist. Graphite, charcoal, and diamond are all allotropes of carbon

Joseph Priestley

Priestley (1733-1804) was hugely productive in research and widely notorious in philosophy. He invented carbonated water and the rubber eraser, identified a dozen key chemical compounds, and wrote one of the first comprehensive treatises on electricity.

But the world recalls Priestley best as the man who discovered oxygen, the active ingredient in our planet's atmosphere. In the process, he helped dethrone an idea that dominated science for 23 uninterrupted centuries: Few concepts "have laid firmer hold upon the mind," he wrote, then that air "is a simple elementary substance, indestructible and unalterable."

J.P’s contributions

Composition of AIR

79%

20%

0% 5% 1% 0%

Composition by volume of clean air

Nitrogen 78-79%Oxygen 20%Carbon dioxide 0.03%Water vapor 0-5%Argon 0.9%Neon and Helium 0.002%

Fractional Distillation of Liquid AirThe liquefied air is passed into the bottom of a fractionating column. Just as in the columns used to separate oil fractions, the column is warmer at the bottom than it is at the top.

The liquid nitrogen boils at the bottom of the column. Gaseous nitrogen rises to the top,

where it is piped off and stored. Liquid oxygen collects at the bottom of the column. The boiling point of argon - the noble gas that forms 0.9%

of the air - is close to the boiling point of oxygen, so a second fractionating column is

often used to separate the argon

Air Pollutio

n

Air PollutionThe condition in which air is

contaminated by foreign substances, or the substances themselves.

Air pollution consists of gaseous, liquid, or solid substances that, when present

in sufficient concentration, for a sufficient time, and under certain conditions, tend to interfere with

human comfort, health or welfare, and cause environmental damage.

AIR POLLUTION CAUSES ACID RAIN, OZONE DEPLETION, PHOTOCHEMICAL

SMOG, AND OTHER SUCH PHENOMENA.

Common Air Pollutants

Effects of Air Pollution to Human Health

The Effects of Air Pollution to the Environment :Acid Rain

Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it

possesses elevated levels of hydrogen ions (low pH). IT CAN HAVE HARMFUL EFFECTS ON

PLANTS, AQUATIC ANIMALS, AND INFRASTRUCTURE.

Acid RainAcid rain is caused by emissions of

sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids.

Acid Rain

. THE CHEMICALS IN ACID RAIN CAN CAUSE

PAINT TO PEEL, CORROSION OF STEEL STRUCTURES SUCH AS BRIDGES, AND

EROSION OF STONE STATUES.

The Formation of Acid Rain

Depletion of the Ozone Layer

The Ozone Layer

WHAT IS THE OZONE LAYER?

THE OZONE LAYER IS A DEEP LAYER IN THE STRATOSPHERE, ENCIRCLING THE EARTH, THAT HAS

LARGE AMOUNTS OF OZONE IN IT. THE LAYER SHIELDS THE ENTIRE EARTH FROM MUCH OF THE HARMFUL ULTRAVIOLET RADIATION THAT COMES

FROM THE SUN.

Is OZONE, OXYGEN?

YES well sort of, technically it’s an allotrope of Oxygen.Ozone is a special form of oxygen, made up of three

oxygen atoms rather than the usual two oxygen atoms. It usually forms when some type of radiation or electrical

discharge separates the two atoms in an oxygen molecule (O2), which can then individually recombine with other

oxygen molecules to form ozone (O3).

Causes of the depletion of O.LYears of research have

determined that CHLOROFLUOROCARBONS

top the list of causes of ozone layer depletion because they are not destroyed by rain or broken down in the lower atmosphere.

Once they reach the stratosphere, the sun’s

ultraviolet rays break down the compound, thus releasing

chlorine. This resulting chlorine is what damages the ozone in a repetitive process. In fact, one chlorine atom will continue to

destroy the ozone for as long as two years.

More about CFC’s & the Ozone

What can we do to protect the ozone layer?

Answer:Since the banning of CFC in industry (Montreal Protocol, 1989),

ozone depletion has mostly stopped with some signs that levels are increasing. Scientists believe that ozone will return to its pre-CFC level by about 2050.

Ways to Protect the Ozone Layer:Minimize high altitude aircraft flights (oxygen reduction and water vapor deposition)Minimize rocket flights (water vapor deposition)Encourage growth of plants that produce oxygen, discourage deforestationDecrease / control releases of high temperature steam / moisture to the atmosphereEliminate production and release of known ozone depleting chemicals (such as CFCs and HCFCs) where remotely possible. Subsidize production of safer alternatives where possible.Establish controls to assure that new compounds to be used in high volume, are surveyed for effect on ozone.

Imagine a world with out TREES that everything was plastic and

you had to buy fresh clean air everyday..

Let it Grow!