CBSE Class 12 · 2011 · Delhi · Chemical KineticsShort Answer

Distinguish between the 'rate expression' and the 'rate constant' of a reaction.

Solution

Rate expression (rate law): the equation expressing the rate of reaction in terms of the molar concentrations of the reactants, each raised to its experimentally found power — e.g. rate

= k [A]^{x} [B]^{y}

. Its value changes as concentrations change.
Rate constant (

k

): the constant of proportionality in the rate expression — numerically the rate when every concentration is 1 mol L

^{- 1}

; at a given temperature it is fixed, independent of concentrations.

CBSE Class 12 Board · 2011 · Delhi · Subjective

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