Transcript Climate Change and Acid Rain

CLIMATE CHANGE
AND ACID RAIN
Basics of Global Warming
Climate Change Tipping Point
Acid Precipitation
pH Scale
Acid Lab
http://www.steinershow.org/files/radio/climate-change-2.jpeg
GLOBAL WARMING
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National Geographic Video http://www.youtube.com/watch?v=oJAbATJCugs&feature=fvw
Picture from: http://earthhabitat.files.wordpress.com/2010/02/greenhouse_effect.png
GREENHOUSE EFFECT
GREENHOUSE EFFECT
Energy from the Sun drives the Earth's weather and climate. The Earth absorbs
energy from the Sun, and also radiates energy back into space. However, much of
this energy going back to space is absorbed by “greenhouse” gases in the
atmosphere (see Figure 1 of Greenhouse Effect). Because the atmosphere then
radiates most of this energy back to the Earth’s surface, our planet is warmer than
it would be if the atmosphere did not contain these gases. Without this natural
“greenhouse effect”, temperatures would be about 60ºF lower than they are now,
and life as we know it today would not be possible.
During the past century humans have substantially added to the amount of
greenhouse gases in the atmosphere by burning fossil fuels such as coal, natural
gas, oil and gasoline to power our cars, factories, utilities and appliances. The
added gases — primarily carbon dioxide and methane — are enhancing the natural
greenhouse effect, and likely contributing to an increase in global average
temperature and related climate changes.
http://www.epa.gov/climatechange/science/index.html
Natural Causes:
• Changes in Earth’s orbit
• Changes in sun’s intensity• Volcanic Eruptions- put CO2 and other greenhouse gases into atmosphere
http://upload.wikimedia.org/wikipedia/commons/9/94/Fluctuations_in_temperature_and_in_the_atmospheric_concentration_of_carbon_dioxide_over_the_past_649,000
_years.gif
CHANGES IN LAST 1,100 YEARS
GLOBAL CLIMATE CHANGE STATS
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http://www.epa.gov/climatechange/
GLOBAL POPULATION CLOCK
http://www.worldometers.info/
WHAT IS ACID RAIN?
• Acid rain- a broad term referring to a mixture of wet and dry deposition
(deposited material) from the atmosphere containing higher than
normal amounts of nitric and sulfuric acids.
• The precursors, of acid rain formation result from both natural sources,
such as volcanoes and decaying vegetation, and man-made sources,
primarily emissions of sulfur dioxide (SO2) and nitrogen oxide (NOx)
resulting from fossil fuel combustion.
• In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come
from electric power generation that relies on burning fossil fuels, like
coal. Acid rain occurs when these gases react in the atmosphere with
water, oxygen, and other chemicals to form various acidic compounds.
• The result is a mild solution of sulfuric acid and nitric acid. When sulfur
dioxide and nitrogen oxides are released from power plants and other
sources, prevailing winds blow these compounds across state and
national borders, sometimes over hundreds of miles.
http://www.epa.gov/acidrain/what/index.html
ACID RAIN
http://www.epa.gov/acidrain/what/index.html
ACID RAIN
• Wet Deposition
• Wet Deposition refers to acidic rain, fog, and snow. If the acid chemicals
in the air are blown into areas where the weather is wet, the acids can
fall to the ground in the form of rain, snow, fog, or mist. 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 several factors,
including how acidic the water is; the chemistry and buffering capacity of
the soils involved; and the types of fish, trees, and other living things that
rely on the water.
• Dry Deposition
• In areas where the weather is dry, the acid chemicals may become
incorporated into dust or smoke and fall to the ground through dry
deposition, sticking to the ground, buildings, homes, cars, and trees. Dry
deposited gases and particles can be washed from these surfaces by
rainstorms, leading to increased runoff. This runoff water makes the
resulting mixture more acidic. About half of the acidity in the atmosphere
falls back to earth through dry deposition.
http://www.epa.gov/acidrain/what/index.html
PH SCALE
• pH is the measure of how acidic or how basic a substance is
• It ranges from 0-14
• A pH of 7 is neutral, a pH of less than 7 is acidic, and a pH greater than 7 is
basic
• The pH scale is logarithmic, meaning… each whole pH value below 7 is ten
times more acid than the next higher value
• Fore example, a pH of 4 is ten times more acidic than a pH of 5 and a
hundred times more acidic than a pH of 6.
• Pure water is neutral, but when chemicals are mixed with water, the mixture
can be come acidic or basic.
http://www.epa.gov/acidrain/education/site_students/images/phscale.gif
ACID LAB
• The strength of acids and bases depends on the relative number of two
chemical substances:
• H+ (Hydrogen ion)
• OH- (Hydroxide ion)
• Example: H2SO4 is sulfuric acid
• In water, H2SO4 breaks down into H+ and HSO 4 ions. The HSO 4- ions
break down further to produce another hydrogen ion (H+) and SO 4- ions
• These free floating H+ ions make a substance acidic
• The more free hydrogen ions in a solution, the stronger the acid is.
ACID LAB
• The pH scale tells us the relative amount of H+ ions in the
solution.
• When the relative number of hydrogen ions is exactly equal
to the number of hydroxide ions, they combine chemically
and cancel each other’s reactivity.
• What substance do we get when we combine an H+ ion with
an OH- ion?
• H2O (Water)
RAIN WATER
• Rainwater is slightly acidic (pH between 5.6 and 5.7)
• Why?
• Some molecules of carbon dioxide from the atmosphere dissolve
into the water and split, releasing the H+ ions into the raindrop.
• What happens to an ecosystem if the rainwater is too acidic?
• Effect of acid precipitation on a body of water depends on the nature of
the rocks and soils in the watershed.
• A watershed with soils high in calcium content or rocks containing
calcium carbonate can buffer acid precipitation
• Think about how Alka Seltzer (Calcium Carbonate) neutralizes
stomach acid
ACID LAB
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You are going to design your own lab to answer a question you might have about acid
precipitation or just the general nature of acids and bases.
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Examples of possible labs:
• pH of different sodas
• pH of different foods
• pH of household products
• What is the best antacid?
• Compare soil samples from around the valley
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Page 38• Write the question you want to answer
• List the variable you will be observing and what data you will be collecting
• On a separate piece of paper, compile a list of materials you need for this lab and have
me check it when you are done.