CHE 310 Midterm Study
negative (balancing) feedback loop-
-is responsible to decrease the function or product of a biological pathway after the end goal has been reached. Ex internal body temperature
Identify the features necessary for a vibrational mode to be IR active-
A molecule will absorb a particular frequency of IR radiation if: that frequency corresponds to the frequency of a molecular vibration that molecular vibration causes a change in the charge distribution of the molecule (has to change the molecular dipole moment) molecular dipole moment= calculation that shows the size of the bond and the difference in electrostatic charges between the molecules in the compound
Identify most significant greenhouse gasses and factors that are resulting in increased emissions
CO2 H2O (Water vapor) (unique because as earth temp increases, so does water vapor which creates a positive (reinforcing) feedback loop) Also created a balancing feedback loop by creating new clouds, which increases albedo, which reflects more radiation and decreases earth's temperature CH4 28x more potent that CO2, Comes from digestive tracts of animals(cows) or decomposition of organic matter, and Usage of fossil fuels (ineffieciently) N2O O3 (ozone) CFCs SF6 Long atmospheric lifetime (3200 years) and 22,800 times worse than CO2
Energy Equation
E = hν = hc/λ, where E = energy, h = Planck's constant, ν = frequency, c = the speed of light, and λ = wavelength Planks=6.62607015 × 10-34 m2 kg / s Speed of light= 3.0*10^8
Describe the role that polar stratospheric clouds play in ozone destruction
First of know polar stratospheric clouds can be abbreviated as PSC^s (confused me for a good minute) There are reactions that happen on the aqueous layer on the surface of PSC^s that don't happen (or happen MUCH slower) in the gas phase Basically converts inactive Chlorine compounds to catalytically active chlorine compounds VERY BAD, this perpetuates catalytic ozone destruction which is fast and reinforcing depletion of ozone
Explain how UV flux vary with altitude in the troposphere and stratosphere
For every 1000 m increase in altitude, the UV radiation level will increase about 12%
Qualitatively evaluate the ozone destruction potential of a gas
Free Radicals of CL,Br, OH and NO ALL BAD (free radicals means it can react with ozone CFCs BAD they form Radical Chlorines HCFCs Are good because they don't form radical Chlorines
UN SDGs, and how can chemistry contribute to achieving them?
GOAL 1: No Poverty GOAL 2: Zero Hunger GOAL 3: Good Health and Well-being GOAL 4: Quality Education GOAL 5: Gender Equality GOAL 6: Clean Water and Sanitation GOAL 7: Affordable and Clean Energy GOAL 8: Decent Work and Economic Growth GOAL 9: Industry, Innovation and Infrastructure GOAL 10: Reduced Inequality GOAL 11: Sustainable Cities and Communities GOAL 12: Responsible Consumption and Production GOAL 13: Climate Action GOAL 14: Life Below Water GOAL 15: Life on Land GOAL 16: Peace and Justice Strong Institutions GOAL 17: Partnerships to achieve the Goal
Explain how pressure vary with altitude in the troposphere and stratosphere
Generally decreases with altitude in all Levels
Explain what is meant by green chemistry
Green chemistry is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances.
Explain how the greenhouse effect works
Greenhouse gasses go up into the atmosphere where they interact with IR radiation released by earth, trapping the heat being released by the earth and then heats the Earth
Describe the conditions needed to form NO2 and O3 in photochemical smog
Inorder for ozone to be formed in photochemical smog you need: NO Volatile organic Compounds Heat Sunlight Stable air mass
Explain the importance of the stratospheric ozone layer
It contains ozone and at this level in the atmosphere it does a great part in absorbing Solar radiation When reaching lower in the stratosphere most UV-C light has been absorbed Protects us from direct UV radiation
what is meant by catalytic ozone destruction
It is the breakdown of ozone using a catalyst By using radical Chlorine the break down of Ozone is made easier and messes up the balance (or balancing system nature of the chapman cycle) leading to a reinforcing system that depletes ozone at higher rates Doesn't have to be Chlorine it can be Br,OH, NO (MUST BE FREE RADICAL)
List the pollutants monitored for the EPA's air quality index
O3 (Ozone) CO Carbon monoxide SO2 Sulfur Dixoide PM2.5 (particulate matter particularly 2.5 micrometers or smaller) NO2 PM10 Lead
Analyze what units are appropriate for a given concentration of gas or type of pollutant
PMs and Lead are measured in ug/m^3 CO,Ozone are measured in ppm SO2 and NO are measured in ppb
List and describe at least 5 (of the 12) principles of green chemistry
Prevention - An often-used measure of waste is the E-factor which relates the weight of waste coproduced to the weight of the desired product. Big in the drug industry Design safer chemicals - Highly reactive chemicals are often used by chemists to manufacture products. science of toxicology requires innovative approaches to chemical characterization that state that hazard is a design flaw and must be addressed at the genesis of molecular design.effort between toxicologists and chemists, focused on training the next generation of scientists to design safer chemicals Use of renewable feedstocks - The concept of making all our future fuels, chemicals and materials from feedstocks that never deplete. Also to help reduce the amount of carbon dioxide that produce into the atmosphere. Ex plant biomass Catalysis- the elimination of waste in the manufacture of chemicals and allied products. Reduction with the former has an atom economy of 81% while reduction with the latter is 100% atom economic, that is everything ends up in the product and, in principle, there is no waste. Real time analysis for pollution prevention- analysis can be performed in-line, on-line, or at-line in a chemical plant, a subdiscipline known as process analytical chemistry. Such analysis can detect changes in process temperature or pH prior to a reaction going out of control, poisoning of catalysts can be determined, and other deleterious events can be detected before a major incident occurs. Ex used in us food and drug administration.
Explain how temperature vary with altitude in the troposphere and stratosphere
Temp Temperature increases with altitude in the stratosphere and thermoshpere Temperature Decreases with increase in altitude for Troposphere (0-15km up) and Mesosphere (50-85 km up)
Explain the difference between the greenhouse effect and the enhanced greenhouse effect.
The natural greenhouse effects are due to the natural occurrence of greenhouse gasses in the atmosphere. Because of the natural greenhouse effect, Earth is warm and supports life. The enhanced greenhouse effect are due to human activities that have led to high concentrations of greenhouse gasses in the atmosphere
Termination:
Two radicals combine with each other to form a non radical species
Apply the steady state approximation to simplify a rate expression
We use this so we can simplify a multi step reaction and be able to calculate its Overall rate Here used to understand the Chapman Cycles rate as a WHOLE not just each step
Primary Pollutants:
are emitted directly from the source Examples: CO,NO,SO2,Pb,PM
Define feedback loop-
defined as the information gained about a reaction to a product, which will allow the modification of the product, it is process whereby a change to the system results in an alarm which will trigger a certain result. Ex stress - than coping with stress lebs back to stress level increase ,
Brundtland Report definition of sustainability
defined sustainability as "meeting the needs of the present without compromising the ability of future generations to meet their own needs." 2 main concepts is the Needs (the worlds poor given priority) and Limitations
Secondary Pollutants:
formed in air from reactions with primary pollutants and each other, other chemicals or light Examples: NO2, O3, PM
which planetary systems have been most affected by people
humanity has exceeded a planetary boundary related to environmental pollutants it stated that society have pushed climate change, biodiversity loss, shifts in nutrient cycles (nitrogen and phosphorus), and land use beyond the boundaries into unprecedented territory. Along with biosphere integrity, Novel entities, biogeochemical flows, climate change
Define flow
is referred to as the quantity that can be measured over a period of time,are entities that make stocks increase or decrease Ex faucet or drain , positive (reinforcing)-occur when an initial change is reinvested to further that change in the future. Ex- Blood clotting
The significance of atmospheric composition
is the absorption of some sun irradiation and its return to the Earth's surface so as to increase temperature (Important to note how much of the atmosphere is a greenhouse gas)
Planetary Boundaries definition of sustainability
nine processes that regulate the stability and resilience of the Earth systems. It is defined as the environmental limits within which humanity can safely operate. Crossing these boundaries increases the risk of generating large-scale abrupt or irreversible environmental changes.
Propagation:
no net generation or loss of radicals; reactants are converted to products
Initiation:
radical species are formed from non-radical species
Define stock-
refers to any quantity that is measured at a particular point in time, stocks are entities that can accumulate or be depleted Ex Bathtub
albedo
the proportion of the incident light or radiation that is reflected by a surface, typically that of a planet or moon. (higher albedo means cooler temp because it's being reflected)
Define system
the set of substances and energy that is being studied, seeks insight into complex networks of interacting molecule Ex water in a beaker/ reactions in a jar. .,