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QJEEM14Ch96dc: JEE Main 2014 Chemistry - Class 12 JEEM14Ch96dc Solution: For the non – stoichiometre reaction 2A + B C + D, the…

For the non – stoichiometre reaction 2A + B →\to C + D, the following kinetic data were obtained in three separate experiments, all at 298 K.
Initial Concentration (A) Initial Concentration (B) Initial rate of formation of C (mol L-1 s-1)
0.1 M 0.1 M 1.2 x 10-3
0.1 M 0.2 M 1.2 x 10-3
0.2 M 0.1 M 2.4 x 10-3
The rate law for the formation of C is:

Multiple Choice Options

  • A dcdt=k[A][B]2{{dc} \over {dt}} = k[A]{[B]^2}
  • B dcdt=k[A]{{dc} \over {dt}} = k[A]
  • C dcdt=k[A][B]{{dc} \over {dt}} = k[A]{[B]}
  • D dcdt=k[A2][B]{{dc} \over {dt}} = k[A^2]{[B]}

Step-by-Step Verified Solution

Let rate of reaction =d[C]t=k[A]x[B]y= {{d\left[ C \right]} \over t} = k{\left[ A \right]^x}{\left[ B \right]^y}

Now from the given data

1.2×10−3=k[0.1]x[0.1]y     ...(i)1.2 \times {10^{ - 3}} = k{\left[ {0.1} \right]^x}{\left[ {0.1} \right]^y}\,\,\,\,\,...\left( i \right)

1.2×10−3=k[0.1]x[0.2]y     ...(ii)1.2 \times {10^{ - 3}} = k{\left[ {0.1} \right]^x}{\left[ {0.2} \right]^y}\,\,\,\,\,...\left( {ii} \right)

2.4×10−3=k[0.2]x[0.1]y    ...(iii)2.4 \times {10^{ - 3}} = k{\left[ {0.2} \right]^x}{\left[ {0.1} \right]^y}\,\,\,\,...\left( {iii} \right)

Dividing equation (i)(i) by (ii)(ii)

⇒    1.2×10−31.2×10−3=k[0.1]x[0.1]yk[0.1]x[0.2]y\Rightarrow \,\,\,\,{{1.2 \times {{10}^{ - 3}}} \over {1.2 \times {{10}^{ - 3}}}} = {{k{{\left[ {0.1} \right]}^x}{{\left[ {0.1} \right]}^y}} \over {k{{\left[ {0.1} \right]}^x}{{\left[ {0.2} \right]}^y}}}

We find, y=0y=0

Now dividing equation (i)(i) by (iii)(iii)

⇒    1.2×10−32.4×10−3=k[0.1]x[0.1]yk[0.2]x[0.1]y\Rightarrow \,\,\,\,{{1.2 \times {{10}^{ - 3}}} \over {2.4 \times {{10}^{ - 3}}}} = {{k{{\left[ {0.1} \right]}^x}{{\left[ {0.1} \right]}^y}} \over {k{{\left[ {0.2} \right]}^x}{{\left[ {0.1} \right]}^y}}}

We find, x=1x=1

Hence d[C]dt=k[A]1[B]0{{d\left[ C \right]} \over {dt}} = k{\left[ A \right]^1}{\left[ B \right]^0}

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