Decomposition class experiment with lime-water and CuCO3?

Question

I put CuCO3 in a test tube. and limewater, Ca(HO)2, in another test tube. I connected both test tubes with a rubber stopper, the rubber end in the tube w/ CuCO3.

I then heated the test tube w/ CuCO3 and a gas traveled through the rubber stopper into the other test tube, which contained Ca(OH)2. The gas gave the limewater a cloudy apperance indicating the presence of CO2 in the limewater.

I saw the chemical reaction, but I have NO clue of how I would write the equation. Could some one please help me figure out how to write the equation?

Answer 1

The thermal decomposition of copper carbonate goes like this:

CuCO3 ----> CuO + CO2.

You should have seen the contents of the heated tube go from green to black, due to copper oxide being formed.

The carbon dioxide reacts with the limewater as follows:

Ca(OH)2 + CO2 -----> CaCO3 + H2O

The white cloudiness is due to the formation of insoluble calcium carbonate.