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A graph plotted between log \: t_{50 \%} vs loga concn is a straight line. What conclusion can you drow from the given graph?

(n=order)

  • Option 1)

    n=1, t_{\frac{1}{2}}=\frac{1}{k.a}

  • Option 2)

    n=2, t_{\frac{1}{2}}=\frac{1}{a}

  • Option 3)

    n=1, t_{\frac{1}{2}}=\frac{0.693}{k}

  • Option 4)

    none

 

Answers (1)

best_answer

As we leaned in concept

First Order Reaction -

The rate of the reaction is proportional to the first power of the concentration of the reaction

- wherein

Formula:

R    \rightarrow        P

a                 0

a-x             x

rate[r]=K[R]^{1}

\frac{-d(a-x)}{dt}=K(a-x)

\frac{-dx}{dt}=K(a-x)  [differentiate rate law]

ln \:[\frac{a}{a-x}]=kt \:(Integrated rate law)

Unit of k=sec^{-1}

t_\frac{1}{2}=\frac{0.693}{k}

 

 

 

We know that for first order reactions, t_{\frac{1}{2}}= \frac{0.693}{k}

\log t_{\frac{1}{2}}= \log (0.0693)- \log k

So, in other words, in a first oder reaction, t_{\frac{1}{2}}  does not depend on the concentration.

Therefore, graphically we can draw.

n=1, t_{\frac{1}{2}}= \frac{0.693}{k}


Option 1)

n=1, t_{\frac{1}{2}}=\frac{1}{k.a}

Incorrect option

Option 2)

n=2, t_{\frac{1}{2}}=\frac{1}{a}

Incorrect option

Option 3)

n=1, t_{\frac{1}{2}}=\frac{0.693}{k}

Correct option

Option 4)

none

Incorrect option

Posted by

divya.saini

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