GE-CHEM 1103 Module 7 Flashcards
may be the least weighty part of the environment, but it is complex
and has a disproportionately large influence on our planet
Atmosphere
total mass of the atmosphere
5.15 ×
10^18 kg
total mass of the atmosphere
the best-known
changes to the atmosphere
increase of CO2
in the atmosphere and the
decrease of ozone in the stratosphere
The Gases of the Atmosphere
Nitrogen (N₂) 780,840 ppm
Oxygen (O2) 209,460 ppm
Argon (Ar) 9,340 ppm
Carbon dioxide (CO₂) 397 ppm
Neon (Ne) 18 ppm
Helium (He) 5.2 ppm
Methane (CH4) 1.8 ppm
Krypton (Kr) 1.1 ppm
Hydrogen (H₂) 0.5 ppm
Ozone (O3) 0.4 ppm
Dinitrogen monoxide (nitrous oxide, N₂O) 0.3 ppm
Carbon monoxide (CO) 0.1 ppm
Xenon (Xe) 0.09 ppm
Radon (Rn) traces ppm
arose from the out-gassing of Earth
when it was simply a molten mass.
Nitrogen
is not the direct source of this element in living beings
Gaseous N2
nitrogen must be in the form to be taken by plants.
usable nitrogen compound, such as
ammonia or ammonium or nitrate ions
Two German chemists, devised a way to
transform nitrogen in the air into fertilizer, using what became known
as the Haber-Bosch process
Fritz Haber and Carl Bosch
method of directly synthesizing ammonia from hydrogen and nitrogen
Haber-Bosch process (https://www.youtube.com/watch?v=o1_D4FscMnU)
involves nitrogen fixation
by soil bacteria or, in aquatic environments, by
cyanobacteria.
Nitrogen Cycle
Steps of Nitrogen Cycle
- The NH4+ ions produced are converted to
nitrate ions, the main form of nitrogen
absorbed by plants - Nitrogen is returned to the atmosphere by denitrifying bacteria, which convert nitrate ions to N2
- Fixation is a chemical process that intends to “lock” tissue, cells, and subcellular
components as close as possible to its original status - Nitrification is a microbial process by which reduced nitrogen compounds (primarily ammonia) are sequentially oxidized to nitrite and nitrate.
had a dramatic effect on
the atmosphere, changing it from a reducing to an oxidizing one
plant life
first began producing oxygen as
long ago as 3.5 billion years
Blue-green algae, or cyanobacteria
Below 17% humans would suffocate, and above 25% all organic
material would burn easily
Oxygen level in the atmosphere
by-product of plant photosynthesis
Oxygen
chemical reaction of photosynthesis
6CO2 + 6H2O → C6H12O6 glucose + 6O2
acts as a shield from the UV-rays in stratosphere. However, it is also a pollutant in troposphere
Ozone (O3)
a legal limit for exposure to ozone in the
workplace
0.1 ppm
is reduced proportional to the level of ozone in the air
Plants growth
Ozone can be formed in two chemical process
- Dissociation of NO2 by ultraviolet rays:
NO2 + energy λ < 240 nm → NO + O
O + O2 → O3 - Dissociation of O2 by radiation with λ < 240 nm :
𝑂2 + 𝑒𝑛𝑒𝑟𝑔𝑦 ↔ 𝑂 + 𝑂
O + O2 → O3
(Note: Ozone also dissociates when absorbs ultraviolet radiation
with 𝜆 < 320 𝑛𝑚
𝑂3 + 𝑒𝑛𝑒𝑟𝑔𝑦 𝜆 < 320 𝑛𝑚 ↔ 𝑂2 + 𝑂
𝑂 + 𝑂3 → 2𝑂2)
leakage of chlorofluorocarbons CFCs in refrigerators and other
domestic appliance causes the depletion of ozone layer
Ozone Hole
Two molecules of chlorofluorocarbons
CFC-114 (C2Cl2F4) and CFC-12 (CCl2F2)
When CFCs diffuse into the stratosphere, they are decomposed by
solar radiation
CF2Cl2 g + UV radiation → CF2Cl g + Cl(g)
destroy large
number of ozone molecules
released of Cl atoms
depletion of ozone layer is described by the chemical reactions
Step 1 - 03(g) + Cl(g) → CLO(g) + O2(g)
Step 2 - CLO(g) + 0(g) → Cl(g) + O2(g)
Step 3 - 03(g) + solar radiation → 0(g) + 02(g)
Net reaction:
2 03(g) → 3 02(g)
essential to life, has the ability to form stable compounds consisting of long chains and rings of atoms.
Carbon
basis of the structures for many compounds that
comprise the living cell
Carbon
trapping of energy in the
Earth’s atmosphere
greenhouse effect
like window glass,
is transparent to incoming solar
radiation
atmosphere
Earth to incoming solar radiation
solar radiation is absorbed and reemitted as infrared radiation
Explain why the Earth is warmer
Gases in the atmosphere, like
window glass, trap some of these
longer infrared rays
The greenhouse effect is caused by certain gases in the troposphere
greenhouse gases
primary greenhouses gases
- Water vapor H2O
- Carbon dioxide CO2
- Nitrous oxide N2O
If Earth did not retain some
energy supplied by the Sun, the average temperature would be too
cold. Life would be impossible
Natural Greenhouse Effect
Much of the concern about global warming surrounds the use of
fossil fuels and one of their products
CO2
This increased concentration will enhance the natural greenhouse effect, causing the planet’s temperature to rise.
CO2
a comprehensive air quality management policy and program
which aims to achieve and maintain healthy air for all Filipinos
Republic Act No. 8749, Philippine Clean Air
Act
