Lab: Acid Rain due to Air Pollutants--Leading to the Clean Air Act | Ms. Laura Branch

Acid Rain due to Air Pollutants--Leading to the Clean Air Act


1.  When we place air pollutants into the atmosphere, such as sulfur dioxide and nitric oxide, they don’t just go away.  They are carried by air currents over great distances and can chemically react with other chemicals in the air. 

·      Write the chemical equation for how nitrogen dioxide, sulfuric acid and nitric acid are formed.  Remember to balance your equations!


2.  When these air pollutants dissolve in rainwater, snow, sleet, fog or dew it is called acid precipitation.  Regular rainwater is slightly acidic (pH 5.1) naturally.  This is due to the presence of carbon dioxide in the atmosphere, which dissolves in the rainwater to form a weak carbonic acid.

·      Write the chemical equation for how carbonic acid is formed from water.  Remember to balance your equations!


3.  Wet deposition refers to acidic rain, fog and snow.  As this acidic water flows over and through the ground, it affects a variety of plants and animals.  The strength of the effects depends on many factors. 

·      Name four factors that will affect the strength of the acidity of the water in the environment.


4. Even though some acidity in precipitation is normal, acid rain is a anthropogenic phenomenon.  It is created when power-production companies and industries burn fossil fuels, such as coal and oil.  This releases sulfur into the air, which combines with oxygen.

·      Explain how the resulting sulfur dioxide can create acid rain/acid precipitation problems for forests miles away.  What types of global wind patterns affect this?  Give an example of three areas in the United States that have been affected by sulfur dioxide, especially in their trees.


5.  Power plants also give off nitrogen oxides (NOx).  When these gases are allowed to dissolve in rainwater they form nitric acid.  Most of the SO2 and NOx released into the atmosphere are from anthropogenic sources.  About 2/3 of all SO2 and NOx comes from electrical power generation that relies on burning fossil fuels like coal. 

·      In Santa Maria, where does our electrical power come from?  How is this electrical power generated?  What type of fossil fuel is used?  What type of pollutant is given off?


6.  Air pollutants that contribute to the formation of acid rain due to the Industrial Revolution and the invention of the combustion engine and extensive use of fossil fuels have had a significant affect of the acidity of rain.

·      Give 3 examples of natural processes of the Earth that contribute to the formation of acid rain.

·      Write the chemical reaction for a combustion reaction using fossil fuels.


7.  Oxides of sulfur and nitrogen are the principal air pollutants contributing to acid rain.    These are mostly produced by from fossil fuel combustion in power plants, industry and vehicles.  Sulfur oxides come from coal burning industry and power plants.  Nitrogen oxides (NO and NO2) are found mainly in vehicular emissions.  The combustion of fossil fuels increase the levels of carbon dioxide in the atmosphere, thereby increasing the amount of carbonic acid formed.  But, carbonic acid accounts for less than 5% of the acid in acid rain.

·      Write a general chemical equation showing the process of sulfur dioxide reacting with water to make sulfuric acid.  (Due to the burning of coal)

·      Write a general chemical equation showing the process of nitrogen dioxide reacting with water to form nitric acid.

·      Write a general chemical equation showing the process of carbonic acid being formed.

·      Draw a picture representing where all three of these types of reactions would occur.


Clean Air Act….

It was during the 1970s that scientists began to observe an increase in acidity in many lakes and streams.  Simultaneously, there was also research into problems associated with the transport of air pollutants such as sulfur dioxide.  Scientists eventually saw the link between the two.  They realized that many power plants used coal that contained high amounts of sulfur as fuel.  It was this sulfur that was being transported via winds and dissolving rainwater to produce acid rain.  When it became apparent that acid rain was a global problem and not solely a local one, the federal government stepped in and started to implement legislation to reduce the emissions of the harmful gases that were the cause of acid rain.  Thus leading to the evolution of the Clean Air Act.  By 2000, sulfur dioxide emissions were reduced 27% since the Clean Air Act started in 1970.


For each of the following, conduct research on the status of The Clean Air Act.  Do this by creating an outline of who, what, where, when, why and how for each part.  Also—give two examples of how an actual area around the world has been impacted.  You information should be put in either a graphic organizer or a timeline of some sort!

·      1967:  Air Quality Act

·      1970:  Clean Air Act

·      1977:  Clean Air Act Amendments

·      1988:  New Source Review challenged in court

·      1990:  Clean Air Act Amendments

·      2002:  Sulfur dioxide reductions (including the sulfur dioxide trading rights

 scheme and allowances.



1.     Which events do you believe have the most significant effect on the environment?

2.     What is episodic acidification and how does it affect lakes?  Give two examples of where this has occurred in the United States.



© Laura Branch 2017