Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Chemical Kinetics and Nuclear Chemistry question

2008 · Shift 0 · Q22
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Chemical Kinetics and Nuclear Chemistry
  5. /2008 · Shift 0 · Q22

Chemical Kinetics and Nuclear Chemistry question

2008 · Shift 0 · Q22

JEE MainChemistryChemical Kinetics and Nuclear ChemistryMCQ+4 / −1
For a reaction 12A→2B{1 \over 2}A \to 2B21​A→2B rate of disappearance of ‘A’ is related to the rate of appearance of ‘B’ by the expression
  1. A
    −d[A]dt- {{d[A]} \over {dt}}−dtd[A]​=12d[B]dt{1 \over 2}{{d[B]} \over {dt}}21​dtd[B]​
  2. B
    −d[A]dt- {{d[A]} \over {dt}}−dtd[A]​=14d[B]dt{1 \over 4}{{d[B]} \over {dt}}41​dtd[B]​
  3. C
    −d[A]dt- {{d[A]} \over {dt}}−dtd[A]​=d[B]dt{{d[B]} \over {dt}}dtd[B]​
  4. D
    −d[A]dt- {{d[A]} \over {dt}}−dtd[A]​=4d[B]dt4{{d[B]} \over {dt}}4dtd[B]​
View written solutionFree

Correct answer: B

  1. Use the stoichiometric rate relation

For a general reaction aA→bBaA \to bBaA→bB the rate is written as −1ad[A]dt=1bd[B]dt-\frac{1}{a}\frac{d[A]}{dt}=\frac{1}{b}\frac{d[B]}{dt}−a1​dtd[A]​=b1​dtd[B]​

  1. Apply it to the given reaction

Given: 12A→2B\frac{1}{2}A \to 2B21​A→2B So, a=12,b=2a=\frac{1}{2}, \qquad b=2a=21​,b=2

Therefore, −1(1/2)d[A]dt=12d[B]dt-\frac{1}{(1/2)}\frac{d[A]}{dt}=\frac{1}{2}\frac{d[B]}{dt}−(1/2)1​dtd[A]​=21​dtd[B]​

  1. Simplify

Since 1(1/2)=2\frac{1}{(1/2)}=2(1/2)1​=2 we get −2d[A]dt=12d[B]dt-2\frac{d[A]}{dt}=\frac{1}{2}\frac{d[B]}{dt}−2dtd[A]​=21​dtd[B]​

Divide both sides by 2: −d[A]dt=14d[B]dt-\frac{d[A]}{dt}=\frac{1}{4}\frac{d[B]}{dt}−dtd[A]​=41​dtd[B]​

  1. Match with the options

This matches Option B.

−d[A]dt=14d[B]dt-\frac{d[A]}{dt}=\frac{1}{4}\frac{d[B]}{dt}−dtd[A]​=41​dtd[B]​

PreviousNext

More from Chemical Kinetics and Nuclear Chemistry

  • Which of the following nuclear reactions will generate an isotope?2007 · MCQ
  • A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room?2007 · MCQ
  • Consider the reaction, 2A + B → products. When concentration of B alone was doubled, the half-life did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this…2007 · MCQ
  • The energies of activation for forward and reverse reactions for A2​ + B2​ ⇋ 2AB are 180 kJ mol−1 and 200 kJ mol−1 respectively. The presence of catalyst lowers the activation energy of both (forward and reverse)…2007 · MCQ
  • Rate of a reaction can be expressed by Arrhenius equation as: k=Ae−E/RT In this equation, E represents2006 · MCQ
  • A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will2006 · MCQ
  • In the transformation of 92238​U to 92234​U, if one emission is an α-particle, what should be the other emission(s)?2006 · MCQ
  • The following mechanism has been proposed for the reaction of NO with Br2​ to form NOBr: NO(g) + Br2​ (g) ⇋ NOBr2​ (g) NOBr2​ (g) + NO (g) → 2NOBr (g) If the second step is the rate determining…2006 · MCQ