In [A]t=ln[A]0−kt( for 1st order reaction ) slope of ln[A]t vs t=−k k=0.0231sec−1 t1∕2=
0.693
0.0231
=30sec Half life is independent of initial concentration. So a plot oft1∕2 vs concentration will give a straight line parallel to x -axis. t90s=
1
0.0231
ln
100
10
=100sec At higher temperature, value of rate constant k increases. So, the slope of the plot ln[A]t vs t will increase and the line will become steeper.