What happens to the carbon dioxide produced when the copper carbonate is heated?

This is in an experiment to create carbon dioxide, where you heat the copper carbonate which is originally green and then it turns black

Thanks

http://en.wikipedia.org/wiki/Thermal_decomposition

Because coper carbonate loses CO3
And turns into copper oxide
Losing CO2 means change in color as well because it has gained oxygen
Since its oxidative state is being changed as well
So the color change is due to this fact...

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