The chemical reaction: 2AgCl (s) → 2Ag (s) + Cl₂ (g) takes place

The chemical reaction:
2AgCl (s) → 2Ag (s) + Cl₂ (g)
takes place

[amp_mcq option1=”in dark” option2=”in sunlight” option3=”on heating” option4=”under high pressure” correct=”option2″]

This question was previously asked in

UPSC NDA-2 – 2024

The correct answer is B) in sunlight.

The chemical reaction shown, 2AgCl (s) → 2Ag (s) + Cl₂ (g), is the decomposition of silver chloride into silver and chlorine gas. Silver halides like silver chloride (AgCl) and silver bromide (AgBr) are known to be sensitive to light. This decomposition reaction is catalyzed by light, particularly sunlight or bright artificial light. This property is fundamental to traditional black and white photography where silver halides in photographic film undergo decomposition upon exposure to light, forming a latent image.

This type of decomposition reaction, which occurs in the presence of light, is called a photolytic decomposition reaction. While some decomposition reactions occur on heating (thermolysis), the decomposition of silver chloride is prominently triggered by light energy. Dark conditions prevent this reaction. High pressure would likely favour the solid reactant over the gaseous product, not cause decomposition.

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