sMOG Flashcards
What are some gases coming from natural sources?
Carbon monoxide, nitric oxide, and sulfur dioxide, ammonia, hydrogen sulfide, and methane.
How are these gases simultaneously removed?
Oxidation by hydroxyl free radicals.
How are hydroxyl radicals produced?
When a fraction of O atoms from O3 photochemical decomposition, react with gaseous water.
Why are hydroxyls so important?
Without it, most pollutive gases would not be removed from the atmosphere
What is smog?
Episodes of air pollution with high levels of ground-level O3
What are the original reactants for smog formation?
Nitric oxide and unburned/partially oxidized hydrocarbons.
What are the sources of emitting smog-forming pollutants?
Internal combustion engines and electrical power plants respectively.
What is the second stage of smog formation?
Formation of VOC reacting in smog.
What are Volatile Organic Compounds?
Chemicals that evaporate easily at room temperature, from some solids to liquids
Why is sunlight also important in smog formation?
Increase of concentration of free radicals participating in smog formation.
What secondary pollutants does sunlight create?
O3, nitric acid, HNO3.
What primary pollutants are responsible for smog?
NO and VOCs.
What do VOC’s like gaseous hydrocarbons emerge from?
Evaporation of solvents, liquid fuels, and other organic compounds.
What are the most reactive VOCs in urban air?
alkenes containing C-C double bond, and aldehydes containing a C-O double bond.
How are free radicals formed from VOC like alkenes?
Hydroxyl radical binds to the carbon, abstracting a H from it, leaving a hydride molecule.