CBSE Class 12-science Answered

Pls answer

Asked by Vidya | 07 Mar, 2019, 07:27: PM

Expert Answer

(a) It is a first order reaction.

From the given data,

At t = 300 sec

Initial concentration [A₀] = 1.6 Χ 10^-2 mol/lit

Final Concentration [A] = 0.8 Χ 10^-2 mol/lit

We have,

The rate of reaction is

straight k space equals space fraction numerator 2.303 over denominator straight t end fraction log fraction numerator open square brackets straight A subscript 0 close square brackets over denominator open square brackets straight A close square brackets end fraction space space space equals space fraction numerator 2.303 over denominator 300 end fraction log fraction numerator 1.6 space cross times 10 to the power of negative 2 end exponent over denominator 0.8 cross times 10 to the power of negative 2 end exponent end fraction space space space equals 0.00767 space cross times log space 2 straight k space equals 2.31 cross times 10 to the power of negative 3 end exponent space sec to the power of minus

Now at t = 600 sec

Initial concentration [A₀] = 0.8 Χ 10^-2 mol/lit

Final Concentration [A] = 0.4 Χ 10^-2 mol/lit

Rate of reaction is,

straight k space equals fraction numerator 2.303 over denominator straight t end fraction log fraction numerator left square bracket straight A subscript 0 right square bracket over denominator left square bracket straight A right square bracket end fraction space space space equals fraction numerator 2.303 over denominator 600 end fraction log fraction numerator 1.6 cross times 10 to the power of negative 2 end exponent over denominator 0.4 cross times 10 to the power of negative 2 end exponent end fraction space space space equals 0.00383 cross times log space 4 straight k space equals space 2.31 cross times 10 to the power of negative 3 end exponent space sec to the power of minus

As the value of rate constant k is constant in both cases, it is the first order reaction.

(a) The half life of reaction,

For first-order reactions,

Half space life space straight t subscript bevelled 1 half end subscript space equals space fraction numerator 0.693 over denominator straight k end fraction space space space space space space space space space space space space space space space space space space space equals space fraction numerator 0.693 over denominator 0.00231 end fraction Half space life space straight t subscript bevelled 1 half end subscript space equals space 300 space sec

The half-life of the reaction is 300 sec.

Answered by Varsha | 08 Mar, 2019, 12:51: PM

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