Question

a first order reaction is 75% complete in 60 min. find the half life of initial reactants that will react in 10 hr

Answer 1

Order of reaction =1
Let initial concentration of reactant be[A]_o =100
[A]_t =100-75=25

Rate law for first order reaction :
k= (2.303/t) log [A]_o/[A]_t
k=2.303/60 log100/25 =0.0231

t_1/2 =0.693/k =0.693/0.0231 =30 minutes.