Science Buddies: "Ask an Expert"

Hello,

I need a consistent and continous CO2 generator. Made a search in Google and here at Science Buddies, and found three possibilities:

1. Yeast generator,
2. Dry ice and
3. CaCO3.

As far as i understood, if I could heat CaCO3 I would free CO2. Two questions:

1. How much heating is needed?
2. Would heating at lower temperatures than the one specified above free any CO2, although at lower rates?

1.) The temperatures required to adequately decompose CaCO3 to CaO and CO2 are somewhere around 800 to 900 degrees Celsius. I recommend the dry ice carbon dioxide generator, since dry ice is cheap ($1/lb?) and you only need to keep it at room temperature to keep it going.
2.) Yes, but not in appreciable amounts. It would be difficult to keep the carbon dioxide from re-reacting with the calcium oxide product and reforming calcium carbonate. I think somewhere around 300 degrees Celsius, the formation of carbon dioxide is equal to the reaction with calcium oxide in forming calcium carbonate.

Hi bereal511,

Thanks for your answer. I really didn't knew the temperatures were so high. Going back to dry ice, or maybe CO2 commercial bottles with needle valves and manometers.