Question

What happens when Calcium carbonate is heated? Silver bromide is exposed to sunlight? Lead is added to copper chloride solution? Write balanced chemical equations of the reactions involved in support of your answer.

Hint:

Heating → Thermal decomposition. Sunlight → Photochemical reaction. Reactive metal → Displacement reaction.

Answer 1

(i) Heating of Calcium Carbonate: Observation: Calcium carbonate decomposes into calcium oxide and carbon dioxide on heating. Type of Reaction: Thermal decomposition reaction \[ \text{CaCO}_3 (s) \xrightarrow{\Delta} \text{CaO} (s) + \text{CO}_2 (g) \] (ii) Silver Bromide in Sunlight: Observation: Silver bromide decomposes into silver and bromine in presence of sunlight, turning grey. Type of Reaction: Photochemical decomposition reaction \[ 2\text{AgBr} (s) \xrightarrow{\text{Sunlight}} 2\text{Ag} (s) + \text{Br}_2 (g) \] (iii) Lead added to Copper (II) Chloride Solution: Observation: Lead displaces copper from copper chloride solution, forming lead chloride and copper metal. Type of Reaction: Displacement reaction \[ \text{Pb} (s) + \text{CuCl}_2 (aq) \rightarrow \text{PbCl}_2 (s) + \text{Cu} (s) \] Conclusion: These reactions illustrate decomposition (thermal and photochemical) and displacement reactions with balanced chemical equations.