Standard:Category:inquiry lesson
Learning Objectives:
1- Students will isolate the sources of CO2 emissions.
2- Students will develop investigative skills.(i.e.
bromthymol blue as an indicator, development of
hypothesis and experiments)
3- Students will discover how carbon dioxide relates to acid
rain and the greenhouse effect.
4- Students will learn the following terms: carbon dioxide,
acid rain, greenhouse effect.
5- Students will discover a cause effect relationship
between fuel consumption and atmospheric polution.
Materials, equipment and/or facilities:
pencils
balloons test tubes, bromthymol blue, string, tape, straws, bicycle
pump (can be used to inflate balloons from a smokey source).
Background:
An effective way to collect car exhaust is with a two inch,
two hole rubber stopper. Tubes are inserted into the stopper. One
tube is to allow the car to idle properly, the other is used to
inflate balloons. Place the rubber stopper into a car that is not
running. Start the car. Also, a bicycle pump is effective in
collecting gas. It can be put in a smoke source, expanded, put
into a balloon and compressed to inflate it.
The relationship between bromthymol blue, CO2, and acid was
covered in an inquiry lesson in standard 1 of Earth Systems.
Teachers may want to choose to review "Bad Breath Test". If
students have not had exposure to bromthymol blue, a bit of
background may be necessary for students to put in their notes.
Humans exhale nitrogen, oxygen, CO2, and water vapor. Among these
things, the CO2 will react with the water to form a weak carbonic
acid. This acid will cause the bromthymol blue to turn green or
even yellow due to its acidic nature.
Sequence and duration of each part of lesson:
Encourage students to take notes on the following
demonstration and discussion. The teacher may even choose to write
ideas on the board. Instruct students that these notes will be
included as part of their lab report.
This activity begins by the teacher modeling the
characteristics of bromthymol blue. The teacher will mix a 5%
solution of bromthymol blue/water in a test tube. This is done in
front of the students so they can learn how to run their own test.
The teacher inserts a straw into the test tube and begins lightly
blowing into the bromthymol solution (or have a student blow),
being careful not to blow too hard or the solution will spill. The
solution will change colors in less than a minute. The teacher
then asks the students inquiry questions such as:
Why did it change color?
What makes it change color?
Could there be something in my breath that causes it?
What other gasses or exhausts could cause such an effect?
After the inquiry questions, the students should be able to
deduct that the cause of the color change is due to the presence of
CO2.
The teacher then should lead a discussion as to -"What harm is
caused by CO2 in the atmosphere?" Answers may vary but important
points should include greenhouse effect, global warming, weather
pasterns, effect on agriculture, pollution, acid rain.
The teacher should then ask,"What are major causes of CO2?"
answers may vary but should include automobiles, factories,
animals, coal fire generation etc.
A challenge to the students is then issued by the teacher.
The students are to:
1- Select and collect a gas or exhaust by any means they can
develop.(encourage the use of balloons)
2- Design an experiment to test for CO2 or other acid causing
emissions. This experiment must be pre approved by the
teacher to ensure safety. This experiment must in include a
hypothesis about their chosen gas as to whether it contains
CO2 or other potentially acidic properties.
The experiment should also include a lab report which
includes:
pre-lab notes
title
hypothesis
procedure
materials
data
conclusion
peer review
3- Conduct the experiment.
4- Record the results. Encourage students to be as quantitative
as possible.(i.e. amount of gas collected, duration of
exposure to bromthymol, concentration of bromthymol, shade of
color change).
5- Report the results to the class.
6- Conclude by conducting a peer review in which the students
compare their conclusions to classmates that tested a like
product. Students should look for results that would support
or contradict their own findings.
Evaluation:
Rubric for evaluating the experiment
4- The students are able to work independently on all
aspects of the task. They formulate a hypothesis and run an
appropriate experiment to test their hypothesis. They collect
accurate data and are able to interpret data. They clearly
communicate results and answer questions concerning data.
3- The students are able to work independently after minimal
assistance. They formulate a hypothesis and run an
appropriate experiment to test their hypothesis. They collect
data and interpret with few mistakes. They are able to
correct errors when pointed out, and they are knowlegable
concering information.
2- The students need prompts and assistance in devolpment of
an hypothesis, procedure and collecting data. The student
runs an experiment but data and interpretation are subject to
error. Attempts are made to correct inconsistancies.
1- Cannot complete task as assigned. The students run an
experiment but has little relevance to hypotheses. The data
is inacurate and there is no attempt to interpret or corect
procedures.