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Carbon Dioxide and Man

Carbon Dioxide

Introduction: (Initial Observation)

Carbon dioxide is the gas that animals (including human) exhale. It is a food for plants and without that no plant can grow. Carbon dioxide is also produced while burning wood, gas or other fossil based fuels. Small amounts of carbon dioxide in the air is harmless, but recently changes in weather patterns known as global warming has raised concerns and there is a strong belief that due to increased level of carbon dioxide, the trapped heat cannot pass through the atmosphere into space because heat’s longer, infrared waves are too large. This causes a rise in the ambient temperature on Earth known as the greenhouse effect.

Some scientists fear that the rise in temperature will disrupt weather patterns, causing the polar icecaps to melt and release more water into the ocean. This increase in water level might cause two things to happen (1) the ocean’s saline concentration would weaken, threatening marine species, and (2) coastal areas would flood.

The build up of carbon dioxide in the atmosphere is caused by:

    1. Deforestation, which reduces the number of trees available to absorb carbon dioxide.
    2. Burning of fossil fuels in power plants.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Adults help and supervision is required

Information Gathering:

Find out about green house effect and global warming. Read books, magazines or ask professionals who might know in order to learn about the effects of carbon dioxide in animals and plants life. Keep track of where you got your information from.

Background Information:

    • The release of carbon dioxide (CO2) gas into the atmosphere is part of a natural process. Plants use CO2 during photosynthesis to make sugars. Plants give off oxygen gas as a result of this process. Humans and other animals use the oxygen expelled from plants as part of their respiration process and expel CO2 gas. This recycling of gases is called the carbon cycle.
    • Fossil fuels are burned to power our homes, schools, and businesses. These fuels are used in vehicles to get us from one place to another. Each year when fossil fuels are burned, billions of tons of CO2 are released into the atmosphere. The CO2 gets trapped in the atmosphere contributing to the greenhouse effect and global warming. In the last 50 years, CO2 in the atmosphere has increased by 10 per cent. Scientists disagree on the severity of the problem, but most agree that the greenhouse effect contributes to global warming.
    • Use of renewable energy technologies is advocated by such groups as: the Union of Concerned Scientists, and the Environmental Protection Agency to reduce greenhouse gases and global warming. This section of the curriculum provides information about these topic areas.


    • carbon dioxide (CO2): a colorless, odorless non-poisonous gas normally present in air. It is vital to plants that absorb it from the air.
    • global warming: a theory that global temperatures are rising as a result of “greenhouse gases” that become trapped in the lower atmosphere.
    • greenhouse effect: excessive buildup of carbon dioxide in the atmosphere resulting in trapped heat.
    • oxygen: an element that at standard temperature and pressure is colorless, tasteless and odorless and is required for nearly all combustion and in the cellular functioning of animals.

Links at the reference section of this project are also good sources of information.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

Sample question:

How will increased level of carbon dioxide in the air affect the temperature of the atmosphere?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Independent variable in our experiment is the amount of CO2 in air and the dependent variable is the heat absorption properties of air.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

The bottle with alka-seltzer will warm up faster and may even keep it’s heat for increase in temperature first. The other container will also warm up but not as much as the container with alka-seltzer in it. This prediction

It supports our predictions because we feel that the alka-seltzer will make the measuring temperature of air heat up more than if there was no CO2.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment 1:

In this experiment we will heat two plastic bottles – one partially filled with water, and the other partially filled with “fizzy” carbonated water, and explore the different rates of heating for the two. The carbonation is created using alka seltzer tablets, and the heating is done using a light bulb positioned between the two bottles.

(A good clear glass bottle or clear plastic bottle is recommended for this experiment, however we have considered using a soda bottle because it is more easily available. )


Take two clear plastic soda bottles ( 2 litter), remove any labels and make sure they are both clean. Cut off the bottle neck so it will have a larger opening. Add water to both bottles to the height of about 1 inch. It is important that both bottles be exact same size with exact same amount of water. In order to create carbon dioxide in one bottle, drop 6 alka-seltzer tablets in that bottle. Then mount one thermometer in each bottle and adjust it to be 12 centimeters from the top of each bottle. Use a tape to secure the thermometer at that position.

Carbon dioxide is heavier than air, so it does not easily exit the bottles. Avoid any air current around the bottles because air turbulence can force carbon dioxide out of the bottle and replace it with air. Next put a light bulb 3 centimeters from each container. Control all variables to make sure that both containers are at exact same conditions and they will both get the same amount of light. Record the temperature every 1 minute for at least 15 minutes. If your light bulb is not strong enough, you may need to extend your experiment time to 30 minutes. Following is a sample table that you can use to record the results of your experiment.

Minutes passed after light exposure Temperature of air bottle Temperature of CO2 bottle

Use the result table to draw a graph. Compare the graphs to see if the temperature of CO2 increased higher and faster than the temperature of air.

Experiment 2: (How can carbon dioxide extinguish fire?)

In this experiment we will build some carbon dioxide and expose it to the flame of a candle to see how does the CO2 gas affect the flame. Carbon dioxide is produced when vinegar and baking soda are mixed.


    • matches
    • baking soda
    • vinegar
    • candle
    • 2 clear cups or glasses or beakers
    • round balloons


    1. Pour 50 ml of vinegar in a beaker
    2. Add 45 grams of baking soda to the beaker
    3. Mix vinegar and baking soda in a beaker so carbon dioxide gas is produced
    4. Tilt the gas over a burning candle. (Do not tilt the beaker or bottle so much that the liquid runs out and extinguishes the flame.)
    5. Explain why the flame went out. Discuss each theory. Repeat the demonstration, explaining each step.


We can “pour” the CO2 gas (CO2 or carbon dioxide is heavier than air) over a flame and extinguish it. The gas will replace the oxygen and without oxygen, the flame will go out.

Materials and Equipment:

List of material can be extracted from the experiment section. The thermometer you use must include the range of 0º Celsius to 100º Celsius or 32º Fahrenheit to 212º Fahrenheit. I suggest a partial immersion glass thermometer such as MiniScience Part# GAT20110

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

In addition to the table and graph write your observations and analysis in this section: Following information are from a similar experiment.

Heat Flow Analysis

At the beginning of the experiment, heat energy flowed into the two containers at different rates.
We know this because the graph showed that the temperature of container with CO2 rose faster than the other container.

Principle Note 1

If an object is transparent, it is easier for the light energy to pass through it.
The bottle and the air are transparent and allow the light to pass through easily without being absorbed.

Principle Note 2

Different materials have different ways in allowing heat energy to pass through.
The heat energy went through the bottle with more CO2 differently than the bottle with less CO2 because the CO2 does not allow heat energy to pass through it
easily as well.
When there is a lot of CO2 in the air from pollution the heat energy from the sun is trapped in the earth’s atmosphere.

Prototype Note 1

On a sunny afternoon, a bird flies into a clean glass window while trying to escape an apartment building. Why did it appear to the bird that the window was open?

The window appears highly transparent because almost all of the light energy that hits the glass passes through it without being absorbed or reflected. Light must reflect off the glass into the bird’s eye for the window to be seen.

This prototype is a good example of the experiment we just ran because the sun is like the light bulb and the light from the light bulb is like the light from the sun. The window is like the bottles. They are both transparent and most of the light traveled through the bottles just like the window.

Prototype Note 2

Kim and Bill drive their cars to the beach. Kim leaves one of her windows slightly open when she parks at the beach.
Bill rolls up all of his windows before he leaves his car.
When Kim and Bill return to their cars after spending three hours on the beach, whose car is hotter inside?

Bill’s car is hotter inside because the car windows do not transmit heat energy as easily as air does. More heat energy is “trapped” in Bill’s car.

This prototype is a good example of the experiment we just ran because when the heat energy is trapped in the car it is like CO2 trapping the heat energy in the bottle. Kim’s car is like the bottle with less CO2 because they both
allow heat energy to flow through it.

Synthesis Note

1. In order to see an object light must reflect off the object and then enter your eyes.
Since the bottle of CO2 were transparent, the light did not reflect into our eyes. You cannot always see transparent materials that keep in heat energy.

2. If more heat energy flows into the object than out of the object then the object’s temperature increases.
The transparent CO2 did not allow the heat energy to flow through it so the temperature of the bottle increased.

3. When light is absorbed by a material, energy in the form of light is changed to energy in the form of heat.
The light energy from the light bulb was changed into heat energy inside of the bottle.


If you do any calculation in relation to your project, write your calculations in your report.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Sample Conclusion

This experiment has added to our understanding about how the CO2 in the air has affected the climate of the earth.
this experiment has shown us that pollution is a great factor in the earth’s climate and the greenhouse affect.
This is an important finding because the earth’s climate depends upon how much water we have, the plants production, and much more. Pollution from cars, aerosol, and factories increases CO2 and other pollutants in the air causing the greenhouse affect.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.