Science Buddies: "Ask an Expert"

Can someone please assist me with plans for a co2 generator? I am attempting to build one to show the amoumts of co2 produced by burning propane.I have a uncle that is a heat and air conditioning mechanic that said he would help if I could get plans.

You need the following: A propane torch or burner (like a stove), a hood to capture the combustion products (CO2), and a scrubber to absorb the CO2. The hood will need a very powerful blower so you can capture all the combustion products and pump them into your scrubber. The scrubber can be a tank of water containing a solution of a soluble Calcium salt . The CO2 will react with Ca ions and form insoluble CaCO2 (limestone). You will need to be sure that the CO2 is well mixed with the water (lots of nozzles?).

You need to research CO2 scrubbers on the web. Just search: Carbon Dioxide + Scrubber and I'm sure you will get enough useful hits.

hold on a sec...

I thought that CaCO3 was limestone (calcium carbonate; carbonate ion = CO3(2-))

paulsdecarli, how do you plan to change CO2 to CO3? (sorry, I do not mean to sound condescending but it just happens to be that way)

aznnerd666

What's a little O between friends?

Kidding aside, dissolved CO2 and calcium carbonate are linked by carbonate equilibrium:

H2O + CO2 = H2CO3
CaCO3 + H2CO3 = Ca+2 + 2HCO-3

This page summarizes it well:
http://www.uh.edu/~jbutler/kunming/carbonates.html

". . .when CO2 increases calcite goes into solution - dissolves. The reverse is also true. Any process that reduces the amount of CO2 in the system will cause calcite to precipitate."

Hey guys thanks for the information but I do not think you understand.I need help in building a generator to produce CO2 by burning propane fuel.I showed the information you have sent to my teacher and he said that my project is to build a generator to produce CO2 from propane.Please help me with this.

Apologies for the confusing comments about CO2 and CO3 - we were getting a little off topic, though it is potentially related to your project.

Propane produces CO2 when it burns. Paulsdecarli described a method that will allow you to generate and capture CO2 from a propane blowtorch. Isn't that what you want to do? If not, let us know and we will suggest something else.