Source Analysis of Carbon Dioxide Emissions
INTRODUCTION
Connecting Carbon Dioxide, Global Warming, and Human Activity
Carbon dioxide is a greenhouse gas. Without the valuable atmosphere, which captures and holds heat, the
surface temperature of Earth would be an estimated average of 2.2ºF or -17ºC. Thus, the atmosphere acts
like a blanket keeping Earth warmer than it would be otherwise, also termed the greenhouse effect because
the same process operates in greenhouses used for growing vegetables in cold climates. A greenhouse is
enclosed and roofed by glass panes, which let sunlight enter, but also absorb the IR emitted back by the
ground, and thus keep the greenhouse warm. IR is infrared radiation, a form of light that doubles as heat
energy.
The chief absorbers of IR in the atmosphere are
not nitrogen and oxygen, the main constituents
of air, but a relatively minor percentage of
“greenhouse gases” such as water vapor (H2O),
carbon dioxide (CO2) and methane (CH4), which
are strong absorbers of IR energy. Once
absorbed the molecules hold onto the IR energy
and increase their molecular vibration, heat.
The carbon dioxide concentrations in the atmosphere have been increasing. Data collected from ice cores
(dissolved CO2) and direct measurements reveal the trend shown in the graph.
Meanwhile, studies from scientists such as James
Hansen at the NASA Goddard Institute for Space
Studies have indicated that the mean surface
temperature of the Earth is also increasing. This
phenomenon is referred to as global warming.
Make note of the graphical data to the left which
indicates the results of weather analysis.
Of course, the questions to answer for which humanity may or may not need to be concerned are the
following. What role have humans played in this new phenomenon? How will these changes affect us?
Copious quantities of research and media information exist on the topic and conflicting viewpoints exist.
Today we will attempt to answer the first of these questions. I will leave the other question for you to
determine based on your own survey of Internet resources and media propaganda.
APPARATUS/MATERIALS:
5 test tubes
Test tube rack OR a 250mL OR 400mL beaker (able to hold all test tubes upright when placed inside)
100mL graduated cylinder
Meter stick OR metric ruler
1 small rubber stopper (size 1 – printed on the end of the stopper)
1 Kimble disposable 1mL glass pipette
4 different colored balloons
4 twist ties
1 250mL Erlenmeyer flask
Bromothymol blue indicator stock solution with 1mL plastic pipette/dropper
Dropper bottle of dilute ammonia solution (1 part ammonia to 50 parts dH 2O)
200mL dilute acetic acid solution
1.3g baking soda
Safety goggles
PROCEDURE:
1) Fill each balloon until it has a 7.5cm diameter according to the following specifications, twisting the
rubber neck of the balloons and securing a twist tie AT LEAST 1cm from the opening at the end of
that balloon. Each balloon’s color should be recorded, OR in the case of duplicate colors, a letter
should be written in permanent marker on the balloon corresponding to it’s sample:
Sample A (Ambient Air) - Use the fish tank air compressors to inflate the balloon to the required
diameter.
Sample B (Human Exhalation) - Have one team member blow up a balloon to the required diameter.
Sample C (Automobile Exhaust) - Meet your instructor outside at the teacher parking lot to have
your balloon inflated. Time your balloon as it is inflated and record your data. Also, assuming your
balloons are “perfect circles” calculate the volume of gas in each balloon.
Sample D (Chemical Reaction) - Pour 200mL of vinegar in the Erlenmeyer flask. Using a funnel, add
1.3g baking soda. Let the mixture bubble for 3 seconds to drive the air out, then slip the balloon over
the neck of the bottle. Inflate the balloon to the proper diameter. If the balloon does NOT inflate to the
appropriate diameter when all bubbling is complete, carefully pinch the balloon to prevent gas escape
and remove it. Repeat the reaction to continue inflating the balloon.
2) Create a hypothesis that ranks the samples in Step 1 from lowest CO 2 concentration (1) to highest CO2
concentration (4). Record your hypothesis on the DOA page.
3) Insert the blunt (NON-tapered) end of the Kimble pipette into the TAPERED end of the rubber
stopper. Do NOT insert it very far—just far enough to insure an airtight fit yet EASY removal later!
4) Pick up balloon A and slip its collar around the wider end (opposite the pipette) of the rubber stopper.
But, DO NOT remove the twist tie yet.
5) Add 15mL of water and 10 drops of bromothymol blue indicator solution to each vial or test tube.
Label the vials A, B, C, D, and E (Control).
6) Place tampered end of the Kimble pipette into and down to the bottom of test tube A and hold it so.
The other lab partner should carefully untwist the tie and balloon to release the gas slowly into the
bromothymol solution. Once the balloon has deflated, gently squeeze the remaining gas from the
balloon through the solution.
7) Repeat the procedure for Step 4 and Step 6 for the remaining balloons and test tubes. In some cases,
the bromothymol blue solution will change color from blue to yellow. Respond to analysis question #1
on the DOA page.
8) Analyze each of the samples by titrating them with drops of dilute ammonia until the bromothymol
blue returns to its original color. Respond to analysis question #2 on the DOA page. Use the control
group as a comparison to determine the end point of the titration, and record the total drops on the
DOA page. (NOTE: If the solution did NOT change color, the n record 0 drops on the DOA page.)
9) Clean up ALL lab materials and make sure that all lab materials are returned to their appropriate
locations at the main lab bench. Be sure to REMOVE your Kimble pipettes from the rubber stoppers.
Balloons may be used again, so PLEASE do not dispose of them.
10) Answer all remaining question in the DOA page.
11)
Source Analysis of Carbon Dioxide Emissions
DATA/OBSERVATIONS:
Time to Fill Balloon C:___________ Estimate Gas Volume:____________ mL
Hypothesis: 1)________ 2)________ 3)________ 4)________
Sample
Color
Titration Drops
A
B
C
D
E
0 (control)
ANALYSIS:
1) What acid in the brothymol blue produces the color change?
2) Write a balanced equation for the neutralization of the substance form #1.
____________ +
NH4(OH) => ____________ +
H2O
3) Was there a change in color of the ambient air? If not, why not? (Doesn’t air
contain carbon dioxide?)
4) What evidence do you have from this lab to support that human endeavors are
contributing the increased levels of CO2 in the atmosphere?
5) List 2 probable effects of global warming over the long-term? Provide source
documentation to support probable effects and state the basics of the support.