Write your observation and a balanced equation for Copper nitrate being heated.

Bluish green crystalline solid, on heating, melts to form a bluish green mass and gives off steamy vapours that condense on the cooler parts of test tube.

${\text{Cu(NO}$3)2}.6\text{H}2\text{O} \xrightarrow{\space \Delta \space} {\text{Cu(NO}3)2} + 6\text{H}2\text{O}

On further heating, the bluish green mass changes to a black residue of copper (II) oxide and brown coloured nitrogen dioxide gas is evolved along with oxygen gas.

$\underset{\text{[Copper nitrate (blue)]}}{2\text{Cu(NO}$3)2} \xrightarrow{\space \Delta \space} \underset{\text{[copper oxide - black]}}{2\text{CuO}} + \underset{\text{[Nitrogen dioxide]}}{4\text{NO}2\uparrow} + \underset{\text{[Oxygen]}}{\text{O}2\uparrow}