Basics of Global Warming

Climate Change Tipping Point

Acid Precipitation

pH Scale

Acid Lab

CLIMATE CHANGEAND ACID RAIN

http://www.steinershow.org/files/radio/climate-change-2.jpeg

GLOBAL WARMING• National Geographic Video http://www.youtube.com/watch?v=oJAbATJCugs&feature=fvw

GREENHOUSE EFFECTPicture from: http://earthhabitat.files.wordpress.com/2010/02/greenhouse_effect.png

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• 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 HSO4 ions. The HSO4- ions break down further to produce another hydrogen ion (H+) and SO4- 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• 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.

• 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

• 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.