A first order reaction is 40%. Complete in 50 minute. How long will it take to 80% complete.

Explanation

`k = (2.303)/(t) "log" ([R]_0)/([R])`
`k = (2.303)/(50) "log" 100/60`
`k = 0.0102 "min"^(-1)`
`t = (2.303)/(k) "log "([R]_0)/([R])`
`= (2.303)/(0.0102) "log" 100/20`
`= 157.82 `min