Carbon Gas Experiment

by Daniel Dalegowski

January 27, 2009, Takilma, OR

Last week the Dome School students created lime water by mixing hydrolized lime and water. This week Kelpie helped them continue the lime water activity and perform the first carbon experiment.

Performing the Experiment

Kelpie explained the process of decanting to the students and they decanted the clear lime water from the jar shown.
The children began the experiment by decanting some of the lime water, being very careful to not mix any of the precipitated calcium at the bottom of the jar. Next, each student was given a drinking glass with some of the lime water. One student asked "We're going to drink it?"

Next Kelpie produced a turkey-baster and demonstrated how it functioned similarly to a lung. When contracted the baster squishes and forces air out; when it's relaxed it forces air back in. It converted kinetic force into air pressure--fascinating!

The turkey-baster was passed from one student to the next. Each student used it to "breath" air from the classroom into his or her glass of lime water. This was not always as easy as it sounds, but each student was able to get a good amount of air circulated through their lime water. There were no noticeable effects on the lime water once the bubbles had escaped.

Next, the students were given straws with which to exhale into the lime water. This was a lot of fun, being the climax of the hands-on portion of the activity--lime water got all over the table and several students dared each other to taste it. One remarked "mmmm, I think I'll have another drink!" (But they didn't like the taste very much.)

Students exhaled into glasses of lime-water. Note the milky, opaque quality of the water.
The result of circulating human breath through the lime water was this: it turned an opaque, milky color. Carbon dioxide (CO2), a biproduct of the student's resparation, had mixed with the lime-water to form Calcium Carbonate (CaCO3), which, while milky and suspended in water at first, will precipitate out of the water and form solid limestone.

This process, in which CO2 was literally taken out of the air, spurred a conversation about carbon sequestering. The kids have already been exposed to many ideas about this; one suggested that carbon be shot into space, perhaps to the Sun. Kelpie said that it might be easier to store carbon here in substances like limestone. One student asked "So, what, we should put lime water respirators on our cars?" That's the beginning of a pretty good idea. A similar system is being tested on several farms in which farm-equipment exhaust is injected into the ground as the fields are tilled, fertilizing and sequestering carbon at the same time.

Kelpie explained that the hydrolized lime used in this experiemnt was hard to find. It's essential for making corn into a highly-nutritious food. Without hydrolized lime, corn is only vagely nutritious , and people have a very hard time living off of it. Kelpie was able to ger her hydrolized lime from a Mexican restaurant--she simply asked and they gave her a pretty big bag of it.

Each of the student's glasses of opaque, milky lime-water was labelled with their names and stored for examination at a later date. The students then moved on to the second part of the experiment: the paperwork.

Research Reports

Lorie and Solomon help the students complete their research reports.
The Dome School kids aver very good at self-motivating in a group: they moved their own chairs to the new table to work on the the reports.

Lorie passed out Science Experiemnt Record Sheets and the students enjoyed writing their names on them. One asked "Does anyone know what we're supposed to be doing?" Some did, and they discussed what the experiment should be named, what it's purpose was, and what the results were. Katherine came and made sure the student's names and dates looked neat and scientific.

Lorie and Solomon helped the students get all the different parts of the report filled out, with first letters capitalized and words spelled correctly. The purpose of the experiemnt was to "test for the prescence of CO2 gas in exhaled breath." Once student complained: "that's too scientific, can you say it again?"

One student asked the group "What's 'procedure'?" to which another student answered "Procedure is how you proceed!" A student stated that he had written that "'we blew through straws' but we have to write more to fill up these lines!" The procedure which the students described was as follows:

  1. Decanted lime water
  2. Poured lime-water into a cup
  3. Blew a few bubbles with the turkey baster into the water
  4. Blew many more bubbles with a straw into the water

Next, the students had to state the results of the experiment. One suggested "It turned white." Lorie responded "You're dangling your particle--don't do that! What is 'it'?" The student replied "The lime water turned white."

Soon, each student had his or her research report filled out correctly; recording all the information about the experiment and the results. It was an excellent review of the activity, reinforcing the concepts visited in the experiment and putting emphasis on spelling, vocabiulary, and understanding.

Wrap Up

Then the class broke for lunch, which the children again served themselves with the help of Katherine and others. Katherine invited Kelpie and I to eat with the students. The lunch was delicious: turkey dogs, salad, home cooked french fries, fruit slices, and carrot and celery sticks.

The Dome School science teacher, Lorie, who worked with the kids on this experiment, is a physcist specializing in lazer optics.

On-line carbon-cycle games are available. The students showed me one which you can play too .