Class 12 NEET Chemistry Chemical Kinetics Questions

For the first order reaction, rate constant is given by, k1=

1

t

‌ln‌

a

a−x

a= initial concentration, (a−x)= concentration at t time
At t=t1∕2,x=

a

2

⇒k1=

1

t1∕2

‌ln‌

a

a− a 2

⇒k1=

1

t1∕2

‌ln‌2
⇒k1=

0.693

t1∕2

Therefore, t1∕2 is independent of initial concentration.