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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?
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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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