rate of reaction =2×10−5 mol L−1 s−1⇒ order of reaction is n=1 rate =K[A]n[ A]=0.01M⇒K=0.012×10−5=2×10−3 K=t1/20.693t1/2=2×10−30.693=346.5 s Related Theory For a first-order reaction, a graph plotted with ln[A] on the Y-axis and time on the X-axis, will be a straight line with a slope of −k. 