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Solve A first order reaction takes 40 minutes for 30% decomposition. Calculate its half life.

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प्रश्न

Solve

A first-order reaction takes 40 minutes for 30% decomposition. Calculate its half-life.

बेरीज
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उत्तर

Given:

[A]0 = 100%, [A]t = 100 - 30 = 70%, t = 40 min

To find:

Half life of reaction (t1/2)

Formula: 

`"k" = 2.303/"t" "log"_10 ["A"]_0/["A"]_"t"`

Calculation:

Substitution of these in above

`"k" = 2.303/"t" "log"_10 100/70`

= `2.303/"40 min" "log"_10 (1.429)`

= `2.303/"40 min" xx 0.155`

= 0.008924 min-1

t1/2 = `0.693/"k" = 0.693/(0.008924  "min"^-1) = 77.66  "min"`

The half life of reaction is 77.66 min.

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पाठ 6: Chemical Kinetics - Exercises [पृष्ठ १३७]

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बालभारती Chemistry [English] Standard 12 Maharashtra State Board
पाठ 6 Chemical Kinetics
Exercises | Q 4. vii. | पृष्ठ १३७

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