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Title: Exploring Carbon Dioxide through Sublimation and Everyday Applications
Principle(s) Investigated:
Main principle investigated is the concept of sublimation as carbon dioxide changes from a solid to a gaseous state.
As carbon dioxide reacts with water during sublimation carbonic acid is produced. Carbon dioxide is one of the major atmosphere gases exhaled by humans and produced by industrialization. Its atomic weight is heavier in comparison to other major gases, this is why helium is used for balloons to stay in the air. Hands-on experiences and visuals are used for students to explore the qualities of CO2 and its effect on our atmosphere.
California Science Standards: (5th-12th)
5th and 8th grade Physical Sciences/Life Sciences-Structure of Matter
5g. Students know properties of solid, liquid, and gaseous substances, such as sugar (C6H12O6), water (H2O), helium (He), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2).
6a. Students know carbon, because of its ability to combine in many ways with itself and other elements, has a central role in the chemistry of living organisms.
Materials:
Tongs- (party city)
Dry Ice- (Ralphs)
Graduate Cylinder (or something similar)
Water
Apple juice
Small plastic cups
Food coloring
Gloves
Plastic small containers (tray for dry ice)
Water bottles
Balloons
Pictures
Projector to show pictures on Flickr
Quickwrite- data collector
Procedure:
Before the lesson, students will arrange in groups of 4 or 5. Each group will receive their materials ahead of time. Materials for each group will be distributed ahead of time as well. A clear bottle halfway full of colored water, a balloon, rubber band, dry ice, and tongs will be placed for each group on student desks.
Prepare:
1. Activate student’s prior knowledge by asking, “What are the main gases that comprise of our atmosphere?” At this time students will enter their responses in the quickwrite.
After collecting data: Show pie chart (first picture in the "Pictures On Flickr" slideshow) to visually show that Nitrogen makes up most of the atmosphere.
Have students hold their breath and exhale to introduce Carbon Dioxide as the gas we exhale and the compound we will be exploring in this lesson. C + O2 ---> CO2
2. Introduce Dry Ice. Explain properties: -109 degrees F
(-78.5 degrees C), Burn/frostbite if touched by hand, Solid form of CO2.
List of uses: http://www.continentalcarbonic.com/dryice/
All about dry ice: http://www.dryiceinfo.com/
3. Pour room temperature water in a graduate cylinder or a household object similar. (Whole class demonstration, picture of two cylinders are shown below. Including YouTube video of activity.)
-Students will predict what will happen if a piece of dry ice is placed in the water.
-Students will observe, discuss with a partner and record their observations.
This is a time to discuss details observed and clear misconceptions students might have.
-What do you notice about the rate of bubbling? (Boiling is a misconception)
(Dry ice is turning into gas; the rate of bubbling slows as the water cools)
-What do you notice about the vapor? Why is it white? (Steam is a misconception)
(Water is so cold that it is condensing water vapor in the air that is why we see white. Hot steam rises unlike CO2 vapor.)
4. Show/explain formula for carbonic acid when CO2 reacts with water.
Real life examples: Soda, Sparkling/fizzing water drinks. Students are watching carbonic acid form when dry ice is
placed in the cylinder and this is what occurs in soda, and sparkling water. Students may make their own fizzing drinks
by placing a small piece of dry ice in apple juice. (Wait for dry ice to sublime before drinking!)
CO2 + H2O ---> H2CO3 (write/read/show formula to class)
5. Sublimation-by passes liquid phase and converts to a gaseous phase.
(special effects in the entertainment industry)
a. Solid to gas heat energy is gained; gas to solid heat energy is released. Heat energy is released or gained when substance is encountering a change of state.
b. Ingredients for sublimation to occur in real life:
Higher altitudes, low pressure, high winds, intense sunlight.
Picture of Mt. Everest!- Sublimation occurs easily at low pressure zones. (second picture on "Pictures On
Flickr" slideshow)
6. Students will continue to further explore dry ice in groups. (Picture of activity for group demonstration is shown below.)
a. Students will place few pieces of dry ice into a water bottle.
b. Quickly place balloon over the water bottle and hold to cover opening as CO2 expands into the balloon.
c. Students will enter observations in the quick-write
d. Similarly to breathing in a balloon, when inflated with CO2 balloons will fall just as the vapor in the beginning of the lesson because CO2 compound is heavier than Nitrogen, Oxygen, and Argon alone.
e. Students will compare a Helium filled balloon to a Carbon Dioxide filled balloon to see that CO2 is heavier than Helium. Refer to "periodic table" link to show atomic weight of He compared to CO2.
Reference the Periodic table of elements http://www.ptable.com/
7. Another example of CO2 expanding into the balloon is the bubble activity which can be demonstrated in front of the class while group demonstration is taking place. This shows that when CO2 sublimes it turns into a gaseous state expanding the bubble, a larger representation. (YouTube video of Dry Ice Bubble is shown below) Discuss- Volume increases from a solid to a gas.
8. CO2 essential to life on earth. It is a natural component of the atmosphere. Human activities in addition to natural phenomena such as volcanoes, geysers and hot springs, increase CO2 in the air making it unnatural. In return, CO2 is one gas that absorbs infrared radiation increasing temperatures on earth. CO2 in the atmosphere can last 1,000’s of years! (show third picture from "Pictures On Flickr" link.)
9. Show pie chart of greenhouse gases, (fourth picture from "Pictures On Flickr" slideshow) showing CO2 has the highest % due to human activities.
Student prior knowledge:
-Students need to know the Scientific Method.
-Students know that Heat Transfer changes the physical property.
-Students know how to read the Periodic Table of elements.
-Change of matter- Nothing can be created or destroyed.
-Students have reviewed atmosphere gases.
-Students know the water cycle. Evaporation, condensation, precipitation.
Following lessons: Greenhouse effect and temperature, Global warming, and carbon cycle.
Example of a following lesson. Investigating the Greenhouse Effect
http://www.tos.org/hands-on/activities/lambert_hands-on.pdf
http://epa.gov/climatechange/kids/basics/today/greenhouse-gases.html
Explanation:
Dry ice is used to show the properties of CO2 gas. Using dry ice engages learners and is used as a visual to demonstrate the concept of sublimation. In this demonstration, integration is used during the process of sublimation to show that when CO2 reacts with water, carbonic acid is produced which is found in soda and sparkling water we drink. CO2 + H2O --> H2CO3
As dry ice sublimes, vapor is released which is used in the entertainment industry for special effects. During this time weight is also discussed in comparison to the other main atmosphere gases when students experiment with CO2 and balloons.
C (12) + O (16) + O (16) = CO2 (44) atomic weight. Explains how vapor falls after sublimation, balloons fall when inflated with CO2.
Students will understand that CO2 occurs naturally in the atmosphere and is used by humans as well. This demonstration will set a foundation for following lessons to come. This eventually will lead into the integration of greenhouse gases and its effect on the atmosphere. Dry ice allows for integration and experimentation and can be used as an example to explain and show many different concepts.
Questions & Answers:
1. Why is CO2 an inefficient gas to keep balloons floating in the air? Why is helium used?
The atomic weight of the compound Carbon Dioxide is heavier than Nitrogen, Oxygen, and Argon alone- the major gases that comprise of the earth’s atmosphere. The atomic weight for Helium is 4.0 which would make it lighter than atmosphere gases and this is why helium is used to inflate balloons.
2. Why do you think sublimation occurs easily at low pressure zones? Such as Mt. Everest?
Pressure is key for change. Low pressure associated with cold weather. Mt. Everest is about 29,000 feet high! Located in Nepal and Tibet. For sublimation to occur, low temperatures, strong winds, intense sunlight, and very low air pressure is needed. Sublimation also occurs more at higher altitudes, where the air pressure is less than at lower altitudes. When pressure is low, the atoms do not require much energy to move, so it is easier for the phase change to occur.
3. Does the CO2 sublime more quickly in water than air? Why?
When CO2 is placed in water in the form of dry ice sublimation is a quicker process. Thinking about heat transfer, water transfers heat more quickly than are at the same temperature. Room temperature water will allow for the property of CO2 to convert to gas. Water molecules are more compact than air. Dry ice will sublime at a slower rate when not in water in high pressure zones like our classroom than Mt. Everest a low pressure zone.
4. Do you think “Dry Ice” a good name for this material? Why or why not?
Dry ice is not composed of water, and it goes straight from a solid state to a gaseous state. Freezer ice, made from water, has to pass through the liquid phase in order to melt. Dry ice does not melt it sublimes!
Applications to Everyday Life:
Carbon dioxide is essential to everyday life. When students understand the qualities of carbon dioxide they will understand when and why sublimation occurs in real life. Students will be able to identify the weather patterns and geographical regions where sublimation occurs such as; mountains and valleys. Next time students drink soda, or sparkling fizzy drinks they will know the drink is a carbonated fluid which occurs during the change of state. By discovering atomic weight of major gases in the atmosphere students will understand why helium is used to keep balloons in the air as apposed to carbon dioxide. With this foundation students will understand that CO2 is a natural component of our atmosphere. Volcanoes, geysers, hot springs can contribute to natural CO2 in our atmosphere but it can be unnatural when human activities such as deforestation, combustion of fossil fuels increase CO2 in the atmosphere contributing to global warming. With this understanding, students will be guided into making their own decisions to care for our earth and its atmosphere.
Photographs: Photos of activities that take place in this lesson.
Videos: Links to videos posted on the web that relate to the activity.
Spangler, S. (2009, July 15). YouTube. Dry Ice Fun-Cool Science Experiments. (Online).
http://www.youtube.com/watch?v=kLO5SJ2uxEE (2012, February 28).
Brunner, M. (2007, October 31). YouTube. Dry Ice Bubble. Steve Spangler. (Online). http://www.youtube.com/watch?v=76CNkxizQuc (2012, February 28).
Create a graph at kidzone! http://nces.ed.gov/nceskids/createagraph/default.aspx
What is dry ice? http://www.continentalcarbonic.com/dryice/
Safety First!
Ken. (2012, January 26). DryIceInfo.com. Design with Merrit & DryIceInfo. (Online).http://www.dryiceinfo.com/ (2012, March 3).
Cody, A. (2004). Cody’s Science Education Zone. Dry Ice! Simply Sublime. (Online).http://tlc.ousd.k12.ca.us/~acody/Dry_Ice.html (2012, March 3).
Dry Ice Bubble!
Ph. D Helmenstein, A. (2012). About.com Chemistry. (Online). http://chemistry.about.com/od/dryiceprojects/a/dryicebubble.htm (2012, March 3).
The Earth’s Atmosphere by Moorland School (Online). http://www.moorlandschool.co.uk/earth/atmosphere.htm (2012, March 3).
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