A first order reaction has a rate constant 23×10−3s−1. How long will it take to reduce 5.0 g of the reactant to 3.0 g?
(Given: log2=0.3,log3=0.5,log5=0.7)
A
20 seconds
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B
30 seconds
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C
40 seconds
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D
50 seconds
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Solution
The correct option is A 20 seconds Applying the first order rate equation k=2.303tloga(a−n)
Where, k= rate constant, a= initial amount of the reactant, a−n= amount of the reactant left after the reaction ∴t=2.30323×10−3log53≈20 seconds