Practical Chemistry — Question 3

(a) Copper carbonate to copper oxide

$\underset{\text{[Copper carbonate (light green)]}}{\text{CuCO}_3} \overset{\Delta}{\longrightarrow} \underset{\text{[copper oxide - black]}}{\text{CuO}} + \underset{\text{[Carbon dioxide]}}{\text{CO}_2} [\text{g}]$

(b) Hydrated copper sulphate to sulphur dioxide

$\underset{\text{[Copper sulphate (hydrous - blue)]}}{\text{CuSO}_4.5\text{H}_2\text{O}}\longrightarrow \underset{\text{ [Copper sulphate (anhydrous - white)]}}{\text{CuSO}_4} + \underset{\text{ [water vapour]}}{5\text{H}_2\text{O}}$

On strong heating

$2\text{CuSO}_4 \longrightarrow \underset{\text{[ Copper oxide - black] }}{2\text{CuO}} + \underset{\text{[Sulphur dioxide]}}{2{\text{SO}_2}} + \underset{\text{ [oxygen]}}{\text{O}_2}$

(c) Copper nitrate to nitrogen dioxide

$\underset{\text{[Copper nitrate (blue)]}}{2\text{Cu(NO}_3)_2} \overset{\Delta}{\longrightarrow} \underset{\text{[copper oxide - black]}}{2\text{CuO}} + \underset{\text{[Nitrogen dioxide]}}{4\text{NO}_2} + \underset{\text{[Oxygen]}}{\text{O}_2}$

(d) Ammonium dichromate to nitrogen

$\underset{\text{[Ammonium dichromate (orange)]}}{(\text{NH}_4)_2\text{Cr}_2\text{O}_7} \longrightarrow \underset{\text{ [Chromic oxide(green)]}}{\text{Cr}_2\text{O}_3} + \text{H}_2\text{O} + \text{N}_2$

(e) Zinc carbonate to zinc oxide

$\begin{matrix} \text{ZnCO}_3 &\xrightarrow\Delta & \text{ZnO} & + & \text{CO}_2 \\ \text{[Zinc} & & \text{[Zinc oxide]} & & \text{[Carbon} \\ \text{carbonate]} & & \text{[yellow - hot]} & & \text{dioxide]} \\ \text{[white]} & & \text{[white - cold]} \end{matrix}$

(f) Zinc nitrate to nitrogen dioxide

$\underset{\text{[zinc nitrate (white)]}}{2\text{Zn(NO}_3)_2} \overset{\Delta}{\longrightarrow} \underset{\text{[yellow - hot, white - cold]}}{2\text{ZnO}} + \underset{\text{[Nitrogen dioxide]}}{4\text{NO}_2} + \underset{\text{[Oxygen]}}{\text{O}_2}$