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Question
A first order reaction takes 40 min for 30% decomposition. Calculate `"t"_(1/2)`.
Solution
Remaining quantity = (a − x)
= a − 0.30a
= 0.70a
k = `2.303/"t" log "a"/("a" - "x")`
= `2.303/40 log "a"/(0.70"a")`
= `2.303/40 log 1.428`
k = 8.90 × 10−3 min−1
`"t"_(1/2)` = `0.693/(8.90 xx 10^-3 "min"^-1)`
= 77.7 min
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