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CBSE Class 12 Chemistry 2022 Term 2 Delhi Set 1

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Question : 1 of 12
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SECTION - A
Answer the following questions (Do any two):
(a) Identify the order of reaction from the following unit for its rate constant: Lmol−1 s−1\mathrm{Lmol}^{-1}\,\mathrm{s}^{-1}
(b) The conversion of molecules AA to BB follow second order kinetics. If concentration of AA is increased to three times, how will it affect the rate of formation of BB ?
(c) Write the expression of integrated rate equation for zero order reaction.
Solution:  
(a) The unit L mol−1 sec−1\mathrm{L}\,\mathrm{mol}^{-1}\,\mathrm{sec}^{-1} for rate constant is the unit of second order reaction.
(b) For reaction A→BA \rightarrow B,
Rate of reaction (r)(r)
=k[A]2.....1=k[A]^2 .....1
If the concentration of reactant increased to three times.
Rate of reaction (r′)(r')
=k[3A]2.....2=k[3A]^2 .....2
Thus, on dividing eq. 1 and 2 .
  rr′  =  k[A]2k[3A]2\;\frac{r}{r'}\;=\;\frac{k[A]^2}{k[3A]^2}
  =  19\;=\;\frac{1}{9}
Therefore, rate of formation of B increases to nine times.
(c) Integrated rate equation for zero order reaction is
k=  [R0−R]tk=\;\frac{[R_0-R]}{t}
Where, k=k= rate constant
  R0=  Initial concentration of reactant  \;R_0=\;\text{Initial concentration of reactant}\;
  R=  Final concentration of reactant  \;R=\;\text{Final concentration of reactant}\;
  t=  time taken  \;t=\;\text{time taken}\;
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