JAMB - Chemistry (2006 - No. 12)
Which of the following typically represents a photochemical reaction?
Formation of water from hydrogen and oxygen molecules
Conversion of dinitrogen (IV) oxide to nitrogen (IV) oxide
Decomposition of calcium hydroxide to its oxide
Conversion of silver halides to grey metallic silver
Explicació
The correct answer is D. Conversion of silver halides to grey metallic silver.
This reaction is a classic example of a photochemical reaction:
2AgCl (silver chloride) + light energy → 2Ag (silver) + Cl₂ (chlorine)
In this reaction, light energy (typically ultraviolet or visible light) initiates the decomposition of silver chloride into silver metal and chlorine gas. This reaction is commonly used in photographic film and paper.