Download Carbon Dioxide in Car Emissions Lab

Carbon Dioxide in Car Emissions Lab
Objective:
o Compare the amount of carbon dioxide present in exhaust fumes
from a variety of vehicles.
o Make predictions about the impacts of the CO2 on Earth’s system of
interacting spheres.
Background
Atmospheric carbon dioxide levels have varied greatly throughout earth's history, with
higher levels often corresponding to warmer periods. Measurements of atmospheric
CO have indicated a steady increase in the last 200 years. Natural sources make up
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the majority of CO emissions and include ocean release, animal and plant respiration,
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organic matter decomposition, forest fires, and volcanic eruptions. Although human
activity accounts for only a small percentage of CO emissions, human output of CO has
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grown steadily since industrialization. This large increase over a short period may have
outpaced the natural carbon cycle's capacity for moderating the atmospheric level,
resulting in a slight but steady rise in atmospheric CO . The major contributors of
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anthropogenic CO are the burning of fossil fuels (oil, coal, and natural gas) and the
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destruction of forests (which take carbon dioxide from the atmosphere during
photosynthesis).
Combustion Engines
Modern automobile engines work by combustion, the burning of fuel. Inside the
cylinders of the engine, fuel is mixed with air at high pressure. A spark inside the
pressurized cylinder ignites the fuel. The energy from this controlled explosion is
converted to mechanical energy that turns a crankshaft and operates the drive wheels
of the vehicle. When fuel is burned, water vapor, carbon dioxide, and various other
chemical products result as pollution. Depending on characteristics of the fuel and the
efficiency of burning, different engines produce exhaust with different composition. To
help reduce air pollution, federal and state laws regulate the amount of emissions
allowed by various engines.
Experiment Design
Independent (Manipulated) Variable = ____________________________________
Condition you will test for; Condition you think will influence the amount of carbon
dioxide
Which vehicle do you think will have higher CO2 emissions? Why?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Sketch/ Describe Experiment Set Up:
Dependent (Responding) Variable = ____________________________________
Condition you will measure to test your hypothesis.
Hypothesis
Formulate a testable hypothesis that communicates which vehicles will emit higher
concentrations of CO . Provide rationale and describe your method for testing your
hypothesis.
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____________________________ vehicles will have higher measured concentrations
of carbon dioxide in their exhaust . This is because …
______________________________________________________________________
______________________________________________________________________
Procedure:
Getting Ready
1. Use a Vernier LabQuest2 fitted with a CO sensor to measure the CO concentration
near the tailpipe of the car.
2. Make sure the switch on the CO Probe is set to “high concentration” (0 to 100,000 ppm).
3. Once you plug in the probe, it will collect concentrations immediately.
4. First, measure CO in the ambient air around you. All measurements and field notes
should be recorded on the field data sheet to 2 significant digits.
5. Repeat this measurement two times.
6. NOTE: at any time, you can hit the record triangle and it will record data in real time to a
file you can save later. This feature is not mandatory.
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Measuring CO at the Tailpipe
1. The concentrations of CO directly at the tailpipe are too high for our probes. So we will
measure at a variety of distances from the tailpipe in order to make comparisons.
2. SAFETY: The tailpipe is hot and would cause a burn it you were to touch it. Don’t touch
it.
3. SAFETY: Don’t inhale fumes. Take note of wind direction to avoid inhaling fumes.
4. IMPORTANT: There is a lot of water vapor in the exhaust from a car. Don’t put the CO
probe any closer than 15 cm as the condensation could damage the probe.
5. First take a measurement at a distance of 30 cm, horizontal to the tailpipe. Record your
data and any field notes.
6. Then take a measurement at a distance of 15 cm, horizontal to the tailpipe. Record your
data.
7. Repeat steps 2 and 3 two times.
8. With your group, decide what additional measurements and observation could be made.
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Results/Data
Measured CO2 Emissions
Vehicle #
Vehicle
Type
CO2 at
CO2 at
________ _______
CO2 at
______
Average
CO2
emission
Comments
Vehicle #
Vehicle
Type
CO2 at
CO2 at
________ _______
CO2 at
______
Average
CO2
emission
Comments
Discussion: Interpret your results
1. Which vehicle has higher carbon dioxide emissions? Use data
(measurements) to support your answer.
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
2. Was your hypothesis supported or rejected? Provide some details.
____________________________________________________________
____________________________________________________________
3. Were there any other factors that may have influenced the amount of
carbon dioxide emissions?
____________________________________________________________
____________________________________________________________
4. Make another hypothesis that you could use to test if the factor you
mentioned above could influence carbon dioxide emissions.
o ____________________________ vehicles will have higher measured
concentrations of carbon dioxide in their exhaust . This is because …
_____________________________________________________________
_____________________________________________________________
5. Describe or sketch out how you would design this experiment.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________