Quick Recap — Rate Laws & Plots

  • Elementary reaction: order == molecularity. For A+B→A+B\to products, rate =k[A][B]=k[A][B].
  • First order: k=2.303tlog⁡[A]0[A]k=\dfrac{2.303}{t}\log\dfrac{[A]_0}{[A]}; a plot of ln⁡[A]\ln[A] vs tt is a straight line (slope −k-k); t1/2=0.693/kt_{1/2}=0.693/k.
  • Zero order: [A]=[A]0−kt[A]=[A]_0-kt; [A][A] vs tt is linear; t1/2=[A]0/2kt_{1/2}=[A]_0/2k.
  • Rate-constant units: order n⇒n\Rightarrow (mol L−1^{-1})1−n^{1-n} s−1^{-1}. Temperature coefficient (rate ratio per 10∘^\circC) ≈2\approx2-33.