UNIVERSIDAD AUTÓNOMA DE NUEVO LEÓN PREPARATORIA NO. 9
CHEMISTRY II Integrative Activity Stage 3
Group 220 Natalia Daenna González Viera Jorge Alberto Cantú Reyes Luis Roberto González Guajardo Andrés Eduardo Reyes Gómez Natividad Aron De León Ramírez
What is Acid Rain? Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog, hail or even dust that is acidic. Acid rain is one of the consequences of air pollution and it has a pH of 5.65 (slightly acid).
Origins When sulfur dioxide compounds and nitrogen oxides accumulate in the air they can reach high levels of concentration in contact with water, oxygen and other chemicals, causing a form of environmental pollution known as acid rain. It should be noted that acid rain can be caused by natural causes such as volcanic eruptions or earthquakes, which release large amounts of pollutants into the atmosphere. But acid rain is also a consequence of man's activities, such as industries or the widespread use of transport using fossil fuels such as gasoline. Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents. The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids. These then mix with water and other materials before falling to the ground. While a small portion of the SO2 and NOX that cause acid rain is from natural sources such as volcanoes, most of it comes from the burning of fossil fuels. The major sources of SO2 and NOX in the atmosphere are: • Burning of fossil fuels to generate electricity. Two thirds of SO2 and one fourth of NOX in the atmosphere come from electric power generators. • Vehicles and heavy equipment. • Manufacturing, oil refineries and other industries. Winds can blow SO2 and NOX over long distances and across borders making acid rain a problem for everyone and not just those who live close to these sources.
Main Emission Sources Some rain is naturally acidic, with a pH level of around 5.0, but human activities have produced an increasing on this pH level. Human activities are the main cause of acid rain. Over the last few decades, humans have released so many different chemicals into the air so that they have changed the mix of gases in the atmosphere. Power plants release the majority of sulfur dioxide and much of the nitrogen oxides, when they burn fossil fuels, such as coal, to produce electricity. In addition, the exhaust from cars, trucks, and buses releases nitrogen oxides and sulfur dioxide into the air. These pollutants cause acid rain. There are some natural phenomena sources that produce acid rain. This natural phenomena, such as volcanic eruptions and some biological processes, release nitrogen oxides, sulfur dioxide, and other gases that react with water to make acid rain. The volcanic eruptions release water vapor and gases such as carbon dioxide and monoxide, sulfur dioxide, hydrogen chloride, hydrogen sulfide, hydrogen fluoride, ammonia, methane and silicon tetrafluoride; these gases react with water vapor to precipitate as acid rain and them produce other consequences to the environment and the human life. The lightning is one of the major sources of localized atmospheric nitrogen, sulfur, and carbon oxides. Lightning bolts reach temperatures of about 30000°C and can transmit a current of up 20000amps; this is powerful enough to cause nitrogen and oxygen in the atmosphere to react and create nitrogen oxide and nitrogen dioxide. The latter dissolves in water vapor to precipitate as weak nitric acid. It also triggers wildfires that emit carbon and sulfur oxides into the atmosphere that in turn MAIN EMISSION SOURCES dissolve in water • HUMAN ACTIVITIES • NITROGEN OXIDE AND vapor and precipitate as carbonic and sulfuric acids. Terrestrial vegetation produces carbon dioxide as part of the transpiration process and when rotting on the ground. Aquatic plants and bacteria emit methane. Other plants emit isoprene, which reacts with nitrogen oxides to produce ozone, organic nitrates and organic acids. All these gases that have been mentioned contribute to the acidification of rainwater.
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NITROGEN DIOXIDE SULFUR DIOXIDE POLLUTANTS VOLCANIC ERUPTIONS BIOLOGICAL PROCESSES LIGHTNING WILDFIRES TERRESTRIAL VEGETATION AQUATIC PLANTS AND BACTERIA
Effects
Acid Rain Can Cause Health Problems in People Air pollution like sulfur dioxide and nitrogen oxides can cause respiratory diseases, or can make these diseases worse. Respiratory diseases like asthma or chronic bronchitis make it hard for people to breathe. The pollution that causes acid rain can also create tiny particles. When these particles get into people’s lungs, they can cause health problems, or can make existing health problems worse. Also, nitrogen oxides cause ground-level ozone. This ground-level ozone causes respiratory problems, like pneumonia and bronchitis, and can even cause permanent lung damage. The health effects that people have to worry about are not caused by the acid rain, but are caused when people breathe in these tiny particles or ozone. Swimming in an acidic lake or walking in an acidic puddle is no more harmful to people than swimming or walking in clean water.
Acid Rain Harms Forests Acid rain can be extremely harmful to forests. Acid rain that seeps into the ground can dissolve nutrients, such as magnesium and calcium, that trees need to be healthy. Acid rain also causes aluminum to be released into the soil, which makes it difficult for trees to take up water. Trees that are located in mountainous regions at higher elevations, such as spruce or fir trees, are at greater risk because they are exposed to acidic clouds and fog, which contain greater amounts of acid than rain or snow.
The acidic clouds and fog strip important nutrients from their leaves and needles. This loss of nutrients makes it easier for infections, insects, and cold weather to damage trees and forests.
Acid Rain Damages Lakes and Streams Without pollution or acid rain, most lakes and streams would have a pH level near 6.5. Acid rain, however, has caused many lakes and streams in the northeast United States and certain other places to have much lower pH levels. In addition, aluminum that is released into the soil eventually ends up in lakes and streams. Unfortunately, this increase in acidity and aluminum levels can be deadly to aquatic wildlife, including phytoplankton, mayflies, rainbow
trout, small mouth bass, frogs, spotted salamanders, crayfish, and other creatures that are part of the food web. This problem can become much worse during heavy downpours of rain or when the snow begins to melt in the spring. These types of events are known as episodic acidification.
Acid Rain Damages Buildings and Objects
Acid rain can also have a damaging effect on many objects, including buildings, statues, monuments, and cars. The chemicals found in acid rain can cause paint to peel and stone statues to begin to appear old and worn down, which reduces their value and beauty.
Conclusion So what we can conclude about this activity after carry out a long and interesting investigation about the dangerous acid rain is that government agencies and scientists are not the only ones that can take action to reduce this problem, this is not a completely difficult problem for the community to help to solve the problem. Everybody can contribute by…
Understanding the Problem The first step you can take to help control acid rain is to understand the problem and its solutions. Conserve Energy Since energy production creates large amounts of the pollutants that cause acid rain, one important step you can take is to conserve energy. You can do this in a number of ways: • Turn off lights, computers, televisions, video games, and other electrical equipment when you're not using them. • Encourage your parents to buy equipment that uses less electricity, including lights, air conditioners, heaters, refrigerators, and washing machines. Such equipment might have the Energy Star label. • Try to limit the use of air conditioning. • Ask your parents to adjust the thermostat (the device used to control the temperature in your home) when you go on vacation. Minimize the Miles Driving cars and trucks also produces large amounts of nitrogen oxides, which cause acid rain. To help cut down on air pollution from cars, you can carpool or take public transportation, such as buses and trains. • Also, ask your parents to walk or bike with you to a nearby store or friend’s house instead of driving. Other Sources of Energy A great way to reduce acid rain is to produce energy without using fossil fuels. Instead, people can use renewable energy sources, such as solar and wind power. Renewable energy sources help reduce acid rain because they produce much less pollution. These energy sources can be used to power machinery and produce electricity.