Question

In a reaction the concentration of a reactant [A] changes from 0.200 mol $ {{L}^{-1}} $ to 50 mol $ {{L}^{-1}} $ in 10 min. The average rate of reaction during this interval is

• A. 0.5 mol $ {{L}^{-1}}{{\min }^{-1}} $
• B. 0.005 mol $ {{L}^{-1}}{{\min }^{-1}} $
• C. 0.35 mol $ {{L}^{-1}}{{\min }^{-1}} $
• D. 0.850 mol $ {{L}^{-1}}{{\min }^{-1}} $

Answer 1

Answer: (B)

$ \Delta \,[A]={{[A]}_{final}}-{{[A]}_{initial}}=[0.150-0.200] $ $ =-\,0.050\,mol\,{{L}^{-1}} $ Average rate of reaction $ =-\frac{\Delta A}{dt}=-\frac{-\,[0.050]}{10} $ $ =0.0050\,\,mol\,{{L}^{-1}}\,{{\min }^{-1}}. $