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Karnataka Board PUCPUC Science 2nd PUC Class 12

A first order reaction has a rate constant 1.15 × 10^−3 s−1. How long will 5 g of this reactant take to reduce to 3 g?

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Question

A first order reaction has a rate constant 1.15 × 10−3 s−1. How long will 5 g of this reactant take to reduce to 3 g?

Numerical
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Solution

For a first-order reaction,

a = 5 g

(a – x) = 3 g

k = 1.15 × 10−3 s−1

t = `2.303/k log  a/((a - x))`

= `2.303/(1.15 xx 10^-3) log  (5)/(3)`

= 2.00 × 103 (log 5 − log 3)

= 2.00 × 103 (0.6990 − 0.4771)

= 2.00 × 103 × 0.2219

= 443.8

≈ 444 S

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Chapter 3: Chemical Kinetics - Intext Questions [Page 78]

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NCERT Chemistry Part 1 and 2 [English] Class 12
Chapter 3 Chemical Kinetics
Intext Questions | Q 3.5 | Page 78

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