IDEAS FOR THE INFORMAL SETTING
OVERVIEW
The accepted sources of carbon dioxide that accord to the greenhouse aftereffect are brought home to your acceptance through this accepted action in which they assay the carbon dioxide agreeable in their animation and in car exhaust.
OBJECTIVES
Students will:
SUBJECTS
Science, Social Science
VOCABULARY
carbon dioxide, exhaust, deposit fuels, greenhouse gases, bittersweet energy, nitrogen, ocean uptake, pH
TIME
1 to 2 sessions added follow-up
MATERIALS
For the class
For anniversary accumulation of four students
For anniversary student
Copies of handouts: Four Gas Samples: Abstracts Breadth and Carbon Dioxide In the Atmosphere: Who Contributes and How Much?
NATIONAL SCIENCE EDUCATION STANDARDS
This action supports the afterward National Academy of Sciences Science Apprenticeship Standards (Grades 5-8):
BACKGROUND
Carbon dioxide is a accustomed basic of Earth’s atmosphere and plays an important role in advancement a adequate temperature on the planet. All animals, including humans, aftermath carbon dioxide aback they breathe. Carbon is additionally appear from rocks through accustomed weathering processes and is appear in the barter of gases amid the oceans and the atmosphere. Added processes such as photosynthesis (short-term) and sedimentation (long-term) blot carbon dioxide. Through this accustomed cycle, Earth maintains a carbon balance.
Human actions, such as the afire of deposit fuels, are abacus carbon dioxide to the atmosphere at a bulk faster than accustomed processes can absorb. The abiding processes that abolish carbon dioxide from the atmosphere (ocean uptake and sedimentation) appointment actual slowly.
As a result, carbon dioxide levels in the atmosphere are increasing. College concentrations of carbon dioxide authority added bittersweet action in the atmosphere than occurs naturally. This added calefaction warms the atmosphere and Earth’s surface. The all-inclusive majority of the accurate association agrees that accretion carbon dioxide in the atmosphere leads to bit-by-bit abating of Earth’s climate.
In this activity, acceptance use bromothymol dejected (BTB) to analysis gas samples for carbon dioxide. They administer the address in an agreement to investigate sources of carbon dioxide in their actual environment. From these tests, acceptance apprentice that the absorption of carbon dioxide exhaled by bodies is beneath than in car exhaust. They altercate the implications of their after-effects for authoritative the amounts of carbon dioxide appear into the atmosphere. Then, through a aftereffect assignment, they apprentice how abundant the assorted nations of the apple accord to the access of carbon dioxide in the atmosphere.
(NOTE: Accepting samples of gas from auto exhausts is abundant easier than it ability seem, and it is agitative for acceptance to see the samples calm in advanced of their eyes. Observing how rapidly the balloons aerate is additionally a bright affirmation of how abundant gas cars absolution into the atmosphere every second. If you are anxious about assurance issues apropos to accepting samples, use developed volunteers to assist.)
BEFORE YOU BEGIN
On the Day Afore the Activity:
1. Adapt the BTB solution. Accomplish a one gallon band-aid of BTB and water. If alpha with the concentrated liquid, ample a one gallon (3.8 liter) canteen 9/10ths abounding with tap baptize and add BTB apply until the band-aid is a deep, cellophane blue. The exact absorption is not critical. However, you should analysis the band-aid by cloudburst ½ oz. (15 ml) band-aid into one of the baby bright cups. Application a straw, airship one lungful of animation through the baby cup of solution. If the band-aid turns green, it is OK. If it stays blue, or alone hardly bluish green, it is too concentrated. Pour out some solution, add added water, and analysis again. If it turns yellow, it is too diluted, and you allegation to add added BTB.
If you alpha with BTB in delicate form, the instructions are the same, except you allegation aboriginal adapt the concentrate. Put 0.03 oz. (1 gram) of BTB crumb into a 2.1 pint (1 liter) container. Add 1.1 tablespoons (16 ml) of 0.1 molar sodium hydroxide (0.1 M NaOH) and deliquesce the crystals of BTB. Add 2.1 pints (1 liter) of baptize to accomplish 2.1 pints (1 liter) of concentrate. For anniversary accumulation of four students, ample a eject canteen with about 6 oz. (0.2 liter) of able BTB solution.
2. Use a car with a annular bankrupt aqueduct (square tailpipes are difficult to seal). Adapt a cone for accession car bankrupt by rolling up a manila binder the continued way. One end allegation be beyond than the aperture of a car’s tailpipe, and the added end allegation be baby abundant for a airship to fit over it. Use affluence of band to authority the cone in appearance and to accomplish the abandon of the cone airtight. Trim the ends of the cone with scissors if necessary. Accomplish a added cone and accept tape, folders, and scissors on duke aback you aggregate the gas. Practice bushing a airship with car bankrupt afore class. Approach the bankrupt aqueduct from the ancillary and authority your animation aback bushing the balloons so you do not drag the gases.
3. Accomplish one archetype of the two-sheet assignment: Carbon Dioxide In the Atmosphere: Who Contributes and How Much? and the Four Gas Samples: Abstracts Breadth for anniversary student. Accomplish one archetype of the Four Gas Samples: Ascertainment Breadth for anniversary accumulation of four students.
On the Day of the Activity:
1. Park the car aural abutting walking distance. Preferably, the chic should not accept to cantankerous a artery to get to the car. Decide breadth the acceptance should angle to watch you aggregate the gas samples so they can see what is happening, but are not in traffic. Back auto bankrupt contains baneful gases, the acceptance should angle aback far abundant so they do not accept to breathe in car exhaust.
2. Assemble the accessories that anniversary apprentice aggregation will need, application trays for accessible distribution. Use the amounts of BTB band-aid adumbrated aloft in this section.
3. Accept the air pump accessible to be anesthetized about from accumulation to group.
WHAT TO DO
Introduction:
1. Introduce the abstraction of all-around abating and altercate why we ability be anxious about levels of carbon dioxide in the atmosphere.
2. Explain that BTB is an indicator that can be acclimated to analysis for the attendance and about absorption of carbon dioxide. On the chalkboard or on the boner paper, draw the calibration of how BTB changes blush aback apparent to altered amounts of carbon dioxide.
3. Explain to the chic that amid the sources of carbon dioxide in the atmosphere are car bankrupt and the animation of bodies and animals. The acceptance will assay the absorption of carbon dioxide from a car’s bankrupt with added samples.
4. Acquaint the acceptance they will booty a abrupt acreage cruise to a car to aggregate samples of exhaust, which they will assay application the BTB method.
Collecting Samples of Car Exhaust:
1. Organize the chic into groups, again affair anniversary accumulation one twist-tie and one balloon. (Bring forth several added balloons and twist-ties, in case you accept breakage. All balloons for the car bankrupt should be the aforementioned color. Additionally accompany the funnel, as able-bodied as an added funnel, folder, scissors, and tape).
2. Acquaint the acceptance to break in groups to chase you outside. Aback you get to the car, they will band up, and one accumulation at a time will duke you their airship for filling.
3. Aback you ability the car, acquaint the acceptance that as anon as you ample their balloons, they are to appointment calm to tie off the close of the airship deeply with the twist-tie. One apprentice should authority the airship closed, while the added apprentice twists the close of the airship to anticipate gas artifice and puts on the twist-tie.
4. Aggregate anniversary of the samples in turn. Aggregate two added samples in case a accumulation loses its sample. Return to the classroom.
Conducting the Experiment:
1. Aback the acceptance are acclimatized into their groups, acquaint them that anniversary accumulation will be testing four gas samples. Account them on the board.
a. Car bankrupt (Point out that the groups already accept their car bankrupt samples.)
b. Air from this room
c. Carbon dioxide from alkali and baking soda
d. Animal breath
2. To aggregate a sample of air from the room, use an air pump to draft up a added airship (of a altered color) to about four inches in diameter. Groups can allotment the pump. Remind the acceptance to appointment calm in pairs while accomplishing the tests, and for anybody to booty turns application the equipment.
3. As acceptance do accomplish 2, 3, and 4 below, they should account the airship blush and gas samples on a abstracted breadth of paper. Later this advice can be transferred to their abstracts bedding that are handed out in footfall 7.
4. Explain why there are bristles cups-relating that four of them are the four gas samples and one of them is the control.
5. Accomplish and aggregate authentic carbon dioxide as follows:
a. Pour 3½ oz. (100 ml) of alkali into a ample bottle.
Measure four akin tablespoons of baking soda into a abstracted container, again add to vinegar. Account these amounts on the chalkboard.
b. The carbon dioxide will drive out all of the air in the canteen in beneath than a second. Quickly amplitude the close of a airship of a altered blush over the aperture to bolt the artifice gas. The airship should aerate to about four inches in diameter.
c. Deeply tie off the close of the airship with a twist-tie. Helpful hint: aberration the airship close anon afterwards accession the gas so no gas escapes afore you get a adventitious to tie it off.
6. Ask the chic how they anticipate they should aggregate the animal animation sample? (Answer: By alarming up a balloon. Accomplish abiding it is a altered blush from the blush alleged for the added gas samples.)
7. Acquaint the acceptance that afterwards they accept calm all four gas samples, they should accomplish them the aforementioned admeasurement by adjusting anniversary airship so it aloof passes through the aperture in a ample aeon of tape.
8. Duke out the abstracts bedding and abridge the procedures.
9. Acquaint the acceptance to almanac on their abstracts bedding which gas sample will be put into which blush balloon.
a. Pour 1/2 oz. (15 ml) of BTB into anniversary of bristles baby artificial cups.
b. Insert a artificial harbinger into the balloon’s neck, and defended it with a added twist-tie.
c. With one actuality captivation the harbinger in the cup, the added actuality anxiously releases burden on the balloon’s close by accident the aboriginal twist-tie, so all the gas boring bubbles through the BTB solution.
10. Afterwards they do anniversary test, they should almanac the blush of the BTB in the amplitude at the bottom.
11. Acquaint the groups to accumulate the BTB band-aid in the cups until the end of the experiment, so they can assay the colors. Aback they finish, they should ample in the names of the four samples forth the band on their abstracts sheets, from atomic to best carbon dioxide. Refer to the calibration you accept fatigued on the chalkboard.
Helpful Hints During the Activity:
1. During the activity, educators should broadcast amid the groups to advice as needed. Watch to see that no baking soda gets into any of the BTB tests (since baking soda is a base, it will abrogate carbonic acid, and anticipate the BTB from alteration to yellow/green). Additionally accomplish abiding acceptance are examination their BTB samples adjoin the white cardboard of the ascertainment breadth afore they actuate the color.
2. Remind acceptance to ample in their after-effects on the “color scale” on their abstracts sheet, which indicates the about amounts of CO2 in the samples, afore they abandon any of their BTB analysis solutions.
3. As the acceptance finish, acquaint them to ample in the final breadth of the abstracts sheet, which asks them to accurate the allegation in writing.
Discussing the Results:
1. Aback all groups accept finished, accept the chic put their accessories (except for the abstracts sheets) on the trays, and put the trays aside.
2. Ask the chic which gas sample had the accomplished carbon dioxide content. Application the calibration on the chalkboard, almanac the results. Ample in names of the added samples the aforementioned way. Aback there are adverse results, account anniversary gas sample and address the cardinal of groups that had anniversary result.
3. Ask the acceptance to attending at the abstracts from all the lab groups and to say what they anticipate the abstracts acquaint us about the bulk of carbon dioxide in according aggregate samples of gas from these sources. (Most groups acquisition that the order, from atomic to best carbon dioxide, is: air, animal breath, auto exhaust, and about authentic carbon dioxide from the baking soda and alkali reaction.)
4. Ask the chic if the after-effects accepted their expectations or if they were afraid at the outcome.
5. Ask the acceptance what added advice they would allegation to actuate the about amounts of carbon dioxide contributed to the atmosphere by bodies breathing, and by bodies active cars. (Answer: They would allegation to apperceive the cardinal of bodies against the cardinal of cars, how abundant time cars are apprenticed on average, the aggregate per minute of gas exhaled by bodies and “exhausted” by cars.)
6. Ask the chic to advance which of the sources of carbon dioxide they accept abstinent (car bankrupt and animal breath) could be reduced. How ability this be done?
7. Remind the acceptance that some carbon dioxide is bald in the atmosphere, or Earth would freeze. The botheration is one of balance. Many advisers anticipate too abundant carbon dioxide is actuality added to the atmosphere from afire deposit fuels such as gasoline, accustomed gas, coal, and oil. These fuels are formed by the adulteration of plants and animals that lived continued ago. Anniversary year bodies bake deposit fuels that adapted about 1 actor years to form. There is no quick way to anamnesis the carbon dioxide from the atmosphere and to alter those fuels. Scientists who accept abstinent the bulk of carbon dioxide from altered sources begin carbon dioxide appear by the United States comes from the afterward sources:
Emissions from electricity generators, which accommodate electricity to the end-use sectors listed above, are allocated appropriately to the electricity captivated in anniversary sector. Taken as a whole, electricity architect emissions calculation for 39.4 percent of the absolute US energy-related carbon dioxide emissions.
The burning of action in the anatomy of deposit ammunition agitation is the better distinct contributor to greenhouse gas emissions in the United States and the world. The better distinct antecedent of emissions is, by far, motor gasoline, which generated 1,143.7 actor metric bags of carbon dioxide in 2003.
Source: Action Advice Administration/Emissions of Greenhouse Gases in the United States 2003, ftp://ftp.eia.doe.gov/pub/oiaf/1605/cdrom/pdf/ggrpt/057303.pdf
8. Duke out the aftereffect assignment, Carbon Dioxide In the Atmosphere: Who Contributes and How Much? Altercate the bar graphs to accomplish abiding the acceptance accept what they represent. For example, ask for a advance to acquaint you:
Ask the acceptance to complete the worksheet and accord them a due date.
ASSESSMENT
The completed abstracts bedding (especially the conclusions) and the accounting answers to the aftereffect appointment worksheet can serve as assessments.
Needs Improvement—Data are incorrect on two or added gas samples; abstracts are ambiguous or incorrect.
Satisfactory—Data actual on gas samples; best or all worksheet answers are correct; abstracts on both worksheets are accepted and correct.
Excellent—Data actual on all gas samples; worksheet answers are correct; abstracts actual and declared in detail.
EXTENSION
MORE INFORMATION
Climate Change Education—An online ability centermost committed to science apprenticeship on altitude change/global warming. www.climatechangeeducation.org
Koshland Science Museum—Global Abating Facts and Our Future www.koshland-science-museum.org/exhibitgcc/index.jsp
Energy Advice Administration www.eia.doe.gov/
IMPORTANT NOTE
When charwoman bottles and cups, artlessly bathe with water. Do NOT use soap! Soap balance will airship and will affect the pH of the gas test. If soap has been acclimated inadvertently, accomplish abiding the bottles are acutely able-bodied rinsed with water.
USING BTB
Bromothymol dejected band-aid (BTB), acclimated actuality to analysis for the attendance and about absorption of carbon dioxide, is an acid/base indicator that measures the pH ambit from 6.0 (yellow) through blooming to 7.6 (blue). The dejected BTB band-aid moves against the chicken (or added acidic) end of the indicator ambit with accretion concentrations of CO2 due to the carbonic acerbic created aback the CO2 is bubbled through water.
BTB is a much-used actinic indicator and is not advised alarming accustomed accustomed precautions and conditions. However, BTB should be handled application accepted lab assurance procedures. Aback advancing the solution, careful gloves and goggles are recommended. While there are little abstracts accessible on adverse bloom effects, spills of BTB on bald bark may be irritating, and the afflicted breadth should be done anon with soap or balmy bactericide and ample amounts of water. If the eyes are affected, they should additionally be done out with ample amounts of water. If BTB is swallowed, it may account gastrointestinal irritation. Do not abet vomiting; get medical absorption immediately.
ACIDS AND BASES
The simplest atom is hydrogen. Its basis is a proton, which has a absolute electrical charge. About the basis is an electron, which has a abrogating electrical charge. Aback a hydrogen atom loses its electron, all that is larboard is the proton. A proton is adumbrated as H back it is the basis of a hydrogen atom and has a net absolute charge.
Chemicals fabricated up of molecules from which protons (H ) may calmly abstract are alleged acids. The protons attach themselves to added molecules amphibian in the water. These absolutely answerable particles accord the acerbic assertive actinic properties. For example, aback alloyed with bromothymol dejected (BTB), acids about-face yellow.
Other chemicals, alleged bases, are composed of molecules from which pairs of hydrogen and oxygen atoms calmly detach. Anniversary of these pairs of atoms has a abrogating electrical charge, adumbrated as OH-.
When acids and bases are alloyed in quantities that accommodate according amounts of answerable particles, this action is alleged neutralization.
Some educators advance a acceptable way to allotment chic advice at the end of this action would be to adapt bristles bright cups, labeled as: Control, Exhaust, Breath, Air, CO2. Afterwards acceptance accept abounding in their abstracts sheets, the abecedary could broadcast about the class, accepting acceptance amalgamate their alone samples into the adapted cup. The colors in the cups would accommodate a color-based chic boilerplate of the results. The bright cups would acquiesce the colors to be apparent on an aerial projector affectation as the chic discusses the results.
More aesthetic analyses of car exhausts appearance that these gases accommodate a aerial admeasurement of CO2. In addition, there are added gases, including oxides of nitrogen (NOx) that acknowledge with baptize to anatomy acids. These gases will accord somewhat to the change in blush of BTB from dejected to yellow. Nitrous oxides are additionally greenhouse gases.
CREDIT
“Sources of Carbon Dioxide in the Atmosphere” reprinted from the Great Explorations in Math and Science (GEMS) teacher’s adviser advantaged All-around Abating and the Greenhouse Effect, absorb by The Regents of the University of California, and acclimated with permission. For added information, appointment the Web armpit at: www.lhsgems.org
Note to Teachers: This assignment and others apropos to National Geographic’s Strange Days on Planet Earth can be begin online at www.pbs.org/strangedays/
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Atoms And Molecules Worksheet
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