Heating CuO and Urea My little brother had to do this experiment at school, but couldn't finish it because of a lack of time. My chemistry knowledge isn't as well as it used to be, so I couldn't be much of an help.

There is a test tube (Tube A) filled with $\ce{CuO}$ and urea. With a glass straw, this is connected to a second test tube (Tube B), which is filled with lime water (which is if I recall correctly $\ce{Ca(OH)2}$?)

A quick sketch:



I really wanted to recreate this at home but I sadly don't have the tools for it.

The question here is: what happens when tube A is heated? (What happens to the material in tube A? What happens to tube B? What is left behind in A? etc).

My guess would be that $\ce{CO2}$ would flow from tube A to B, but I am not sure even about that.
Heating a hydrocarbon with $\ce{CuO}$ generally evolves $\ce{CO2}$ and $\ce{H2O}$. Urea is no exception for this rule.
The $\ce{CO2}$ evolved will turn lime water milky(this is a test for $\ce{CO2}$ gas).