CBSE Class 12 · 2002 · Delhi Compartment · Chemical KineticsShort Answer

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Why does the rate of most reactions increase when the temperature of the reaction mixture is increased? In what units is the rate of a reaction expressed?

Solution

On raising the temperature, the kinetic energies of the molecules increase; the fraction of molecules possessing energy equal to or greater than the activation energy rises steeply (the Boltzmann distribution shifts), and the collision frequency also increases a little — so the number of effective collisions, and hence the rate, increases markedly (roughly doubling per 10° rise).
Units of rate: mol L

^{- 1}

^{- 1}

(for gaseous reactions, also atm s

^{- 1}

CBSE Class 12 Board · 2002 · Delhi Compartment · Subjective

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