CBSE Class 12 · 2001 · Delhi Compartment · Chemical KineticsVery Short Answer

The reaction

2 H_{2} (g) + O_{2} (g) ⟶ 2 H_{2} O (l)

is thermodynamically feasible. How is it that a mixture of hydrogen and oxygen kept at room temperature shows no tendency to form water?

Solution

Thermodynamic feasibility (

Δ G < 0

) says nothing about speed.
The reaction has a very high activation energy; at room temperature a negligible fraction of molecules possesses this energy, so effective collisions are practically absent and the reaction rate is immeasurably slow. (A spark or catalyst, by providing/landing the activation energy, makes it explosive.)

CBSE Class 12 Board · 2001 · Delhi Compartment · Subjective

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