Basic physical science and introductory chemistry can be fun and easy with a few creative ideas. Students can learn about the physical properties of carbon dioxide, why it's important, and what it can be used for by participating in some simple experiments. Below are a few suggestions to spark creativity.
What is Carbon Dioxide?
Carbon dioxide is a gas found in Earth's atmosphere in trace amounts. It is in the air as only 0.038% of the atmosphere. Scientists write carbon dioxide as CO2 because it is made of one carbon atom bonded to two oxygen atoms.
Plants use CO2 while people and animals exhale it. CO2 is usually found as a gas but can also be found as a liquid in some fire extinguishers or in its solid form as dry ice. As a gas it is not harmful by itself but it can be too cold and dangerous to touch as a solid or as a liquid.
There may be some confusion between carbon dioxide and carbon monoxide, which is a dangerous and poisonous gas. Make sure students understand that although they are similar, they are also very different.
Creating a CO2 Molecular Model
To help students understand the molecular structure of CO2, consider having them create a model of carbon dioxide. Students can create a complex model with two completed oxygen model atoms connecting to a carbon model atom, or they can create a simpler model with a carbon sandwiched between two oxygen atoms.
There are many different ways to create a visual representation of CO2. For example, students could use a tennis ball as the carbon and two identical rubber balls as the oxygen molecules. The ball representing the carbon should look different from the balls representing the oxygen. The carbon ball could be connected to the oxygen balls with wire, skewer sticks or even super glue.
Greenhouse Effect, the Climate, and CO2
Everyone has heard about the greenhouse effect but not everyone understands what a greenhouse is or what is meant by the greenhouse effect. Discuss what a greenhouse is, how it is made, and what it is used for. If possible, go to a greenhouse. They can be found in many places including some universities, zoos, arboretums, and nurseries. If visiting a greenhouse is not an option, consider contructing a small greenhouse for the classroom.
CO2 is emitted in various ways, including from plants, from burning fossil fuels, and from volcanic eruptions. Discuss the greenhouse effect and global warming with students. What do they think about comparing Earth to a greenhouse? What are the similarities and differences? Encourage discussion and original thinking, beyond what they may have heard. For those students who are interested, allow them to do in-depth research projects on the greenhouse effect and global warming.
Dancing Raisins
A fun experiment requiring only raisins, a glass and clear, carbonated soda is the Dancing Raisins experiment. Pour soda into the glass, then drop a few raisins into the glass. Observe the raisins as they fall to the bottom of the glass. Soon, some of the raisins will float up and then sink down.
Why are the raisins dancing up and down in the glass? See if students can figure out the answer. Carbon dioxide is what gives the soda its fizz, or carbonation. The tiny fizzing bubbles are the carbon dioxide trying to get out of the soda. When enough bubbles attach to a raisin, they lift the raisin up as they rise to the surface of the soda. When the bubbles escape, the raisin falls again and again begins to collect more carbon dioxide bubbles.
Respiration in Plants - Breathing in CO2
People and animals breathe in oxygen and exhale carbon dioxide. Plants need carbon dioxide and give off oxygen. Does having differing levels of CO2 affect plant growth?
Have students observe that plants use CO2 during photosynthesis. Make sure they understand the concept of photosynthesis. Include the chemical formula for the reaction of photosynthesis.
- carbon dioxide + water ==> glucose + oxygen
- 6CO2 + 6H2O ==> C6H12O6 + 6O2
For an experiment, have two identical plants. They should be the same type of plant, the same size of plant, in the same type of dirt and in the same type of pot. They should be in an area with adequate, but not excessive, heat and sunlight. Put one plant in a large plastic bag and seal it. Monitor the plants and observe their growth and overall health. Which plant is healthier and why?
Baking with CO2
What causes bread to rise and cookies and cakes to be light, airy and fluffy? It's carbon dioxide! CO2 is released from things like yeast, baking soda, and baking powder in chemical reactions.
If possible, have students bake bread with yeast and bread without yeast. Compare the two. They could also try baking cookies or cakes, using baking soda or baking powder in one batch and eliminating it in the second batch. Have them notice the differences in the final products.
Carbon Dioxide pH Testing
PH indicators will be needed for these activities. First, test the pH of water, either tap water or distilled water. Then test the pH of carbonated water, such as club soda or seltzer water. Carbon dioxide added to water makes carbonic acid, so the pH test should show the carbonated water to be acidic.
People exhale carbon dioxide. Have students exhale through a straw into water. The water should then test as acidic because of the exhaled CO2 creating carbonic acid in a chemical reaction with the water.
Carbon Dioxide from Baking Soda and Vinegar
Follow standard laboratory safety procedures for all experiments. Pour a small amount of vinegar into a cup or beaker. Test the pH of the vinegar. It should show acidic on the pH test.
Pour a small amount of baking soda into a cup or beaker. Add some water and stir to create a baking soda and water solution. Test the pH of the baking soda solution. It should show as a base on the pH test.
What happens if the vinegar is added to the baking soda solution? Ask students what they think will happen, then add the two together. There should be bubbling as the baking soda reacts with the vinegar causing CO2 to be released in a chemical reaction. Test the pH of the resulting solution. It should be neutralized.
There are many other activities students could explore while studying carbon dioxide. When the lessons are done, they should realize the importance of CO2. They should know it is a colorless, odorless gas that affects the world around them in many different ways. Students who are interested could do further research on CO2, including preparing a science fair project on some aspect of carbon dioxide.
Angela Kleinow - I graduated from the University of Michigan, where I focused on Science Fiction and Fantasy for my senior seminar while working with the ...
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