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For general reaction \mathrm{X\rightarrow Y, } the plot of concentration of X vs time is given in the figure. What is the order of the reaction and what is the units of rate constant?

 

Option: 1

\mathrm{Zero, mol L { }^{-1} \mathrm{~s}^{-1} }


Option: 2

\mathrm{First, mol L s { }^1 }


Option: 3

\mathrm{First, \mathrm{s}^{-1} }


Option: 4

\mathrm{Zero, L mol s { }^{-1}}


Answers (1)

best_answer

For a zero-order reaction, concentration versus time graph is a straight line with a negative slope.

Consider a zero order reaction,

Rate, \mathrm{R=K[A]^0}

\mathrm{-\frac{d[A]}{d t} =K[A]^0 }

\mathrm{-\frac{d[A]}{d t} =K \times 1 \\ }

\mathrm{-d[A] =K d t }

Taking limit on both side

\mathrm{-\int_{[A]_0}^{[A]_t} d[A]=K \int_0^t d t }

When
\mathrm{ \text { time }=0, \quad A=[A]_o \\ }

\mathrm{ \text { time }=t, \quad A=[A]_t \\ }

\mathrm{ -[A]_{[A]_o}^{[A]_t}=K[t]_0^t \\ }

\mathrm{ {[A]_0-[A]_t=K t} \\ }

\mathrm{ {[A]_t=[A]_0-K t} }

Its in y=m x form.

Hence, Plot between \mathrm{ [A]_t } vs time :

Hence,
Order of the given reaction is zero
\mathrm{ \text { Rate }=\text { Rate constant }=\frac{d x}{d t} }
units of \mathrm{ \mathrm{K}=m o l L^{-1} s^1 }.

 

Posted by

Rishi

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