CBSE Class 12 · 2020 · Chemical KineticsShort Answer

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Analyse the given graph, drawn between concentration of reactant vs. time (see figure).
(a) Predict the order of the reaction.
(b) Theoretically, can the concentration of the reactant reduce to zero after infinite time? Explain.

Structure Concentration of reactant vs time — Concentration of reactant vs time

Solution

(a) The concentration falls exponentially with time — the curve of a first order reaction:

[R] = [R]_{0} e^{- k t}

(b) No. Since

[R] = [R]_{0} e^{- k t}

, the concentration becomes zero only when

t \to \infty

; the exponential curve approaches the time axis asymptotically and never actually touches it.

CBSE Class 12 Board · 2020 · Subjective

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