Question

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)

Answer 1

Half life t1/2 = 0.693/k

k = 0.693/69.3 = 1/100 = 0.01 min^-1 

For first order reaction