## A first-order reaction takes 69.3 min for 50% completion. What is the time needed for 80% of the reaction to get completed?

## (Given: log 5 =0.6990, log 8 = 0.9030, log 2 = 0.3010)

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Answer:
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Half life t1/2 = 0.693 /k

k= 0.693/69.3 = 1/100 = 0.01 min
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For first order reaction

π = 2.303/π‘ πππ [π π]/[π ]

π‘ = 2.303/0.01 πππ 100/20

π‘ = 230.3 log 5 (log 5 =0.6990)

t= 160.9 min