Reactions and the Environment Chapter 4

1) Fossil Fuel Combustion Fossil fuels: energy resources from the decayed remains of prehistoric plants and animals (coal, oil, gas) Usually these ‘remains’ need to be converted to other forms of energy via combustion they provide around 66% of the world's electrical power, and 95% of the world's total energy demands (including heating, transport, electricity generation and other uses). Ex. octane (gas) + oxygen CARBON DIOXIDE+ WATER+ ENERGY

Negative Impacts of Combustion Incomplete combustion: when there is not enough oxygen available, fossil fuels do not burn completely. Complete combustion produces 3 products, they are? Incomplete combustion produces 5 products: carbon monoxide, carbon, carbon dioxide, water, and energy 1) CARBON MONOXIDE is poisonous: Over a lifetime of continued exposure, a person's ability to transfer oxygen and rid pollutants is impeded. Those affected could become afflicted with fatal asthma attacks and other serious lung conditions. 2) CARBON DIOXIDE is a greenhouse gas: it traps heat in Earths atmosphere, which cause increased global temps.

This is causing Global Warming: Gradual increase in the average global temperature, which is linked to sea levels rising, glaciers melting, destructive weather patterns, climate zone and habitat destruction Also this is causing Climate Change: climates are changing much more quickly than they did in the past, which is eliminating many habitats and organisms

Air Pollution -Incomplete combustion releases carbon dioxide and other pollutants into the air. These pollutants cause such problems as: asthma, eye/nose/throat irritation, heart and lung conditions -Some of these pollutants that are released by cars, fires, volcanoes, smokestacks, etc., react with other pollutants in the atmosphere and create ACID RAIN/ PRECIPITATION **Sulfur and Nitrogen oxides are the key pollutants that cause acid rain

Impacts Acid Rain Highly industrialized areas

How to Reduce Acid Rain and Depositions Sulfur and nitrogen oxides are the main reason for acid depositions Removal of sulfur from fuel before the fuel is burned decreases the amount of sulfur oxides in the atmosphere Burn/use ‘sweet’ natural gas: decreased amounts of sulfur For coal, a scrubber is used to remove sulfur from the coal that is being burned

2) Acid-Base Reactions 1) Occurs in the body: stomach produces hydrochloric acid to eat away/digest food, BUT this acid also eats away the digestive system lining. To prevent this, the pancreas releases bicarbonate ions (base) into the small intestine to neutralize the acid 2) Occurs in the environment: The government uses limestone to neutralize lakes and bodies of waters that have been affected by acid rain. This is called Liming use calcium carbonate

3) Corrosion of Iron = any process that chemically breaks down or degrades metal Best known case is called rusting Rusting is a simple composition rxn 4Fe + 3O2  2Fe2O3 (iron oxide = ‘rust’) OXYGEN is the key reactant, without oxygen rusting could not occur!

What to do about rusting? 3 main ways to prevent rusting 1) Painting: painting over iron acts as a protective coating over the surface of metal, but what happens when the paint chips off? 2) Galvanizing: a process of applying a ‘zinc coating’ to iron 3) Sacrificial Metal: a second metal that is more reactive than iron placed near iron, thus oxygen reacts with it and not iron Usually magnesium is used