KCET2015ChemistryChemical Kinetics
Half life period of a first order reaction is ( 10 ~min ). Starting with initial concentration ( 12 M ), the rate after ( 20 ~min ) is
Options
- A( 0.0693 M ⁻¹ )
- B( 0.693 3 M ⁻¹ )
- C( 0.0693 3 M ⁻¹ )
- D( 0.0693 4 M ⁻¹ )
Correct answer
C. ( 0.0693 3 M ⁻¹ )
Step-by-step solution
For first order reaction, Half -life is ( t 1 2 =10 ~min ) [ k= 0.693 10 =0.0693 ~min ⁻¹ ] As ( t_ 1 2 ) is ( 10 ~min ), so, after ( 20 ~min ) or two half-life the conc. will be ( 3 M ). ( 12 M t_ 1 / 2 ) Hence, the rate ( =0.0693 3 M ~min ⁻¹ )