A first order reaction takes 100 min for completion of 60% of the reaction. Find the time when 90% of the reaction will be completed

Explanation

If a first order reaction is 60% complete in 100 min.
Let `[x]_(0) = 100 M, [x]_(60%) = 100 - 60 = 40" M" and t =100" min"`
`k = (2.303)/( t) log"" (x_0)/( x) = (2.303)/( 100 ) log"" (100)/(40)`
`=0.02303 log 2.5 `
`0.02 303 xx 0.397 = 0.009" min"^(-1)`
Time taken to complete 90% reaction `=?`
`[x]_(0) = 100 M, [x]_(90%) = 100-90 = 10M`
`k = 0.009" min"^(-1)`
`t = (2.303)/( k) log"" (x_0)/( x) = (2.303)/( 0.009) log"" (100)/(10)`
`=255.8 log 10 = 255.8" min"`