Chem Quiz 1 Flashcards
What does O2 in the planetary atmosphere indicate?
It is the litmus test of life, as only life can produce O2, so its presence signals the presence of life
H2O signals potential for life, where o2 signals fulfillment
What did Priestly discover? When?
He discovered O2 in 1774 by focusing sunlight onto mercuric oxide
2Hg + 2Hg +O2
What did Lavoisier discover?
He proved that O2 is the reactive constituting of air.
He vaporized diamonds (which are made of carbon) by heating them in the presence of O2. He created a combustion reaction.
C + O = CO2
He showed that combustion and human respiration are fundamentally the same, both consuming O2 as as well as materials which contain carbon
Free radical theory
Ageing is caused by breathing O2 over a lifetime
(Involves damage of cellular constituents by free radicals)
States that O2 is not only necessary for life, but also the primary cause of aging and death.
O2 is not only essential and beneficial for life but also _____
Toxic
Depending on concernetation and duration of exposure.
Animals die below 16%
When animals are exposed to 75% oxygen their lungs become severely inflamed and leads to their demise a few short days later
Who were Haldane and Oparin?
In the 1930s they thought about the possible composition of the earths original atmosphere based on gases identified in the atmosphere of Jupiter (optical spectroscopy)
What is thought of the earths original atmosphere?
If earth condensed from a cloud of gas/dust, its original atmosphere must have contained a similar noxious mixture as Jupiter:
- h2, CH4, NH3, gases from volcanic activity (CO2, H2O, N2,H2S)
-did not contain O2, a reducing atmosphere
What is the Miller-Urey Experiment
In 1953, they simulated early earth by passing electric sparks (lightning) through a gaseous mixture which resembles the atmosphere of early earth. Days later, a brown solution was obtained and amino acids where detected.
Could we have evolved from hydrothermal vents?
Yes,
At hydrothermal vents on the ocean floor, organisms use the oxidation of sulfur compounds so as energy sources.
Ex. Pyrolobus fumarii and picophilus torridus
What is the snowball earth hypothesis?
Tropics were covered with glaciers 1km thick at multiple points throughout history
What are the two hypothesis’ for the snowball earth?
1) O2 used up the methane. Since methane is more potent than CO2, a decline in GHG potency reduces atmospheric temperature
2O2 + CH4 = CO2 +2H2O
2) tectonics. All land mass was free of ice and when continental rocks are exposed to air, they are eroded by dissolved CO2. And with CO2 consumption due to photosynthesis as an added factor, the CO2concentration in the atmosphere declines
Who was pasteaur?
He stated that yeast and anaerobic organisms exist today as relics of a i cent life, as the first cells presumably evolved in an O2-free atmosphere
What were the first photosynthetic bacteria?
Cyanobacteria (work as stromatolites, proving that they superseded singe celled life in oceans)
How are Cyanobacteria related to the great oxygenation event?
Cyanobacteria started to pollute their environment with toxic O2 waster. This produced O2 that reacted with minerals that are dissolved in oceans (iron). Only after this buffer is used up, O2 began to build up 2.2-2.0 billion years ago. This wiped many microbes out in the great oxygenation event
How did the snowball earth go away?
Volcanic activity
Eruptions release CO2, no photosynthesis or rock erosion on an ice-covered planet, so GHG builds up, causing warming.
The cyro-ecosystems that survived the snowball earth left high levels of nutrients in glaciers, causing a bloom of Cyanobacteria and a rise in free O2
Why did the Cambrian explosion occur?
The rise of O2 in the atmosphere produced from the bloom of Cyanobacteria after the snowball earth caused the Cambrian explosion
Rising O2 levels opened new horizons for Precambrian life. The Cambrian explosion was caused by the interplay between genetic possibility and environmental opportunity
O2 is ____ but not _____ to the evolution of multicellular organisms
Linked, but not causal
How did the ozone layer form? What is it?
Rising levels of O2 post snowball earth.
The ozone reduces penetration of damaging UV rays to the surface of the earth by 70%, creating a protective shield or “earths natural sunscreen”.
what is the GAIA hypothesis? Who formulated it?
Co-evolution of macroscopic and microscopic events on earth
Lovelock and Margulis
Atmosphere, biosphere, oceans and soil constitute a complex system which seeks optimal conditions fro biota. Possible homeostasis on a planetary scale? (Not many scientists support this view)
How do we know CO2 concentration over time?
Ice core data, gas gets trapped as snow is deposited. The entrapped gas is encased in amber.
What is the troposphere?
10km in altitude
- vertical mixing (stove), barrier for H2O vapour, 85% of mall of atmosphere
What is the Aurora borealis?
When free electrons are recaptured by ionized gases
What is the stratosphere?
10-50Km altitude
Temp increase, slow vertical mixing (stratified)
What is the mesosphere?
50-80km in altitude
Very thin air, strong vertical mixing
What is the thermosphere?
80+km, extending into outer space, characterized by steadily increasing temperature with height
Like a vacuum
What is the ionosphere ?
100-400km
Ionization of atmospheric gases
Where earths atmosphere meets space
Contains high concentration of ions and free elections and is able to reflect radio waves
What are the concentration units for atmospheric gases?
Absolute concentrations
Relative concentrations
What are absolute concentrations?
Units for measuring atmospheric gases
Molecules per cm3
Expressed as partial pressure (ideal gas law)
What are relative concentrations?
Units for measuring atmospheric gases
Mole fraction scale
Expresses the number of molecules of a pollutant that are presents in 1 million (billion, trillion) molecules of air
100ppm
What is the electro magnetic spectrum ?
Wavelength ranges of greater environmental interest
What is UV-C
The 200-280nm region where O3 and O2 filter out all UV light
What is the UV-B region?
From 280-320 nm
Ozone is not completely effect in shielding us from light i this region
What is the UV-A region?
320-400nm
UV-A doesn’t penetrate to the surface
What wavelengths must UV light have in order to reach earths surface ?
Greater than or equal to 220 nm, as it is filtered by O2 above the stratosphere
What do we use the absorption spectrum for ?
To distinguish between interaction of molecules with electromagnetic ration in UV, visible and infrared radiation light range
What is a photochemical rxn?
Any rxn initiated by light
What is vibrational energy?
The rotational motion of a diatomic molecule
Molecules with three or more atoms generally have some vibrations that absorb infrared radiation
What are the modes of energy in a molecule?
Vibrational energy (oscillation on bonds)
Rotational energy (like a microwave)
And translational
Which molecules can absorb infrared radiation?
Only molecules which have a permanent or induced dipole moment
What is a dipole moment? Why is it important
When the center of mass does not equal the center of change, that is a dipole moment
Certain vibrations can induce a dipole moment
If a molecule is experiencing a permanent or induced dipole moment, it can absorb infrared radiation
What is albedo?
The fraction of sunlight reflected back into space by an object
The ratio of reflected radiation divided by incoming solar radiation
Think of the algal bloom
How is heat transferred to the poles?
50% is atmospheric transport (think different cells)
50% is ocean circulation
Can global ocean circulation be affected by climate change?
Yes
Right now, warm surface water flows norward from the tropics towards the North Atlantic, bringing heat to Europe.
It is speculated that a rise in temperature and rainfall could weaken or eliminate this pattern, as it has happened in teh past
What is earths albedo?
0.3
What is the El Niño
A band of warm water that develops near Peru
Occurs every five years, not understood how it forms
Westerly winds push surface after west, upwelling and good fishing in Peru, and rainy in Indonesia
What is upwelling
Deep cold water rises toward the surface
What is the greenhouse effect
The result of the buildup of CO2 and other greenhouse gases in the atmosphere
Increase global temperatures
What makes a greenhouse gas
- Must absorb infrared radiation
- Must be long lived
- Must have a sufficient concentration to affect the global radiation budget.
What are the Noble gases in the atmosphere
Cannot absorb IR
N2 78%
O2 21%
Ar
Ne
What are the greenhouse gases in the atmosphere
H2O 0.5-3%
CO2
CH4
O3
What are CFC’s ?
Chlorofluorocarbons (CFC-12, CFC-11) absorb rational
Have no tropospheric sink, so all molecules eventually rise up into the stratosphere. They are then broken into chlorine which depletes the ozone
How do greenhouse gases affect the radiation budget?
Because CO2 and H2O absorb in the wavelength range where earth emits energy
The more GHG in the atmosphere, the more infrared radiation is reflected, and the warmer it will get
What is radiative forcing?
Radiative forcing is a measure of the change in energy balance as a result of a change in a forcing agent (e.g., greenhouse gaseous, aerosol, cloud, and surface albedo) to affect the global energy balance
The change in average net radiation at the tropopause due to the change either in incoming solar radiation or outgoing infrared radiation
What does positive infrared radiation indicate?
Net warming
What does negative infrared radiation indicate?
Net cooling
After a volcanic explosion, what can we expect in terms of infrared radiation?
Ash is spewed into the stratosphere and increases the scattering of solar radiation, which mean less solar energy is coming in, and results in a NET COOLING and a NEGATIVE RADIATIVE FORCING
What is the role of aerosols in radiative forcing?
40% of net warming of all greenhouse gases is cancelled by anthropogenic aerosols
The cooling effect of sulphate aerosol mostly in the northern hemisphere, due maiming to industrial activity, outweighs the greenhouse gas heating effect in some regions
AEROSOLS DO NOT ACCUMULATE, WHERE GHG’S DO (get washed out by the rain)
What is Global Warming Potential? (GWP)
A measure of how effective a greenhouse gas is relative to CO2
Help policy makers to be informed on the relative importance of a GHG on future warming
It is the total radiative forcing over time for a kg of GHG released now, relative to the total radiative forcing overtime for a kg of CO2 released now.
What are the artificial sources for CO2?
Fossil fuel consumption
Forest clearing and wood burning
What are the natural sinks for CO2?
Oceans (CO2 and H2O making carbonic acid)
Forests (photosynthesis)
Soils
What are the sources of methane?
Methonigenic bacteria’s anaerobic decomposition of organic matter (in the wetlands)
Anthropogenic coal mines, gas distribution leaks, landfills
What are methane sinks?
Conversion to CO2 (ie.Landfills burning methane)
Stratosphere
What are N2O sources?
Nylons production (40%)
What are N2O sinks?
The stratosphere
What are sources of CFC’s
100% anthropogenic causes . Dipped due to Montreal protocol
What are the general average annual temperature trends?
US/Canada warming
Arctic circle is warming more rapidly than everywhere else
SE USA and china experiencing cooling
Effecting average precipitation
EXTREME WEATHER BECOMING MORE COMMON
What can we do in the face of global warming?
- Adapt (CO2 sequestration by various methods)
- Mitigation buildup if atmospheric GHG (reduce fossil fuels, alter politics and lifestyle choice to Forster decarbonization)
Why can’t we use the ocean for CO2 storage?
Shallow — CO2 would return to the atmosphere
Deep — carbonic acid would exterminate sea life
Neutral — drained in depth
What is the Chapman mechanism?
A series of reaction that was first proposed by Sidney Chapman to explain the presence of the ozone layer in the earth’s stratosphere
How is O3 destroyed?
A catalytic chain reaction (Chapman mechanism 1) which it is converted to O2 by a chain carrier
What is a free radical?
An atom or molecule with an unclaimed electron, so it is very reactive
Mechanism 1 vs mechanism 2?
Mechanism 1:
0 + 02 –> 03
Mechanism 2:
203 –> 302
What are the candidates for free radical X?
NO (natural catalysts that takes O3 and makes O2)
Atomic CL and Bromine (Cl can destroy 10,000 molecules of ozone, the natural compound is emitted from oceans and tropical plants) (99% of Cl is catalytically inactive)
Why has tropospheric ozone increased?
Since pre industrial times, it has increased from power plants, vehicles, grass/forest fires
What is smog?
Smoke + fog
SO2 and particulate matter
When undefinable concentrations of ozone due to light induced chemical reactions cause photochemical smog
What are the chief reactants in smog ?
NO (internal combustion engines and electrical power plants)
Unburned hydrocarbons (engines, evaporation of fuels and organisms, and VOC’s
Light from the sun
What is a VOC?
Volatile organic compounds are organic compounds that have a high vapor pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample’s molecules in the surrounding air, a trait known as volatility.
Ie. benzene
What are the conditions for smog to occur?
Substantial traffic and dense population (NO, VOC)
Ample sunlight (climate, no clouds)
Little movement of air (geography)
What is the photochemical reaction that produces smog?
VOC’s + NO + O2 produces ozone and HNO3 and organics
The ground level ozone creates eye and nod lung damage, very toxic
