A first order reaction is 20% complete in 10 minutes. What is the specific rate constant for the reaction?

Options

A. `0.0970 "min"^(-1)`
B. `0.009"min"^(-1)`
C. `0.0223"min"^(-1)`
D. `2.223"min"^(-1)`

Answer

C

Explanation

`k = (2. 303)/( 10) log "" (100)/( 100 - 20)`
`k = ( 2.303)/(10) log"" (100)/( 80)`
`k = (2. 303)/( 10) log "" (10)/( 8) = (2.303)/( 10) [ log 10 - log 8]`
`k = (2. 303)/( 10) [ I - 0.903]`
`k = (2.303)/( 10) xx (0.097)/( 10 ) = 0.00223 "min"^(-1)`