Question

a first order reaction is 15% complete in 20 minutes how long will it take to complete 20%​

Answer 1

Answer:

30.03min

Explanation:

For first order reaction-

k =[ 2.303log(R/r)]/t     ......eq1    

                                                                R = initial conc.

 r = R -15%of R                                        r = conc. at t.

   = R -  15R/100

  = 85R/100

k = 2.303log(100/85)/20

  =  2.303log(1.17)/20

 =  2.303*0.06/20

 = 0.0069/min

r = R-20% of R

 = 80R/100

t  =  2.303log(100/80)/0.0069

     = 2.303*0.09/0.0069

     =30.03(min)