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Chemical Kinetics · Question 48

AIPMT 2010 (Prelims)MCQEasy📈 Topic in 0% papers+4−1
1

For an endothermic reaction, energy of activation is Ea and enthalpy of reaction is H (both of these in kJ/mol). Minimum value of Ea will be

  1. less than H
  2. equal to H
  3. more than H
  4. equal to zero

Answer

(3) more than H

Solution

For an endothermic reaction the products lie higher in energy than the reactants by H.

The activated complex (transition state) lies above the products, so

Ea = H + Ea' (where Ea' = activation energy of the backward reaction)

∵ Ea' > 0

∴ Ea > H; the minimum value of Ea is more than H (it can at best approach H).

Answer: (3)

AIPMT 2010 (Prelims)

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2

For the reaction N2O5(g) 2NO2(g) + 12O2(g) the value of rate of disappearance of N2O5 is given as 6.25 10-3 mol L-1 s-1. The rate of formation of NO2 and O2 is given respectively as

  1. 6.25 10-3 mol L-1 s-1 and 6.25 10-3 mol L-1 s-1
  2. 1.25 10-2 mol L-1 s-1 and 3.125 10-3 mol L-1 s-1
  3. 6.25 10-3 mol L-1 s-1 and 3.125 10-3 mol L-1 s-1
  4. 1.25 10-2 mol L-1 s-1 and 6.25 10-3 mol L-1 s-1
AIPMT 2010 (Prelims)
3

During the kinetic study of the reaction, 2A + B C + D, following results were obtained array|l|l|l|l| Run & [A]/ mol L-1 & [B]/ mol L-1 & Initial rate of formation \ & & & of D/ mol L-1 min-1 \ I. & 0.1 & 0.1 & 6.0 10-3 \ II. & 0.3 & 0.2 & 7.2 10-2 \ III. & 0.3 & 0.4 & 2.88 10-1 \ IV. & 0.4 & 0.1 & 2.40 10-2 \ array Based on the above data which one of the following is correct?

  1. Rate = k[A]2[B]
  2. Rate = k[A][B]
  3. Rate = k[A]2[B]2
  4. Rate = k[A][B]2
AIPMT 2010 (Prelims)
4

For the reaction, N2 + 3H2 2NH3, if d[NH3]dt = 2 10-4 mol L-1 s-1, the value of -d[H2]dt would be

  1. 4 10-4 mol L-1 s-1
  2. 6 10-4 mol L-1 s-1
  3. 1 10-4 mol L-1 s-1
  4. 3 10-4 mol L-1 s-1
AIPMT 2009
5

In the reaction, BrO-3(aq) + 5Br-(aq) + 6H+ 3Br2(l) + 3H2O(l). The rate of appearance of bromine (Br2) is related to rate of disappearance of bromide ions as

  1. d[Br2]dt = - 53 d[Br-]dt
  2. d[Br2]dt = 53 d[Br-]dt
  3. d[Br2]dt = 35 d[Br-]dt
  4. d[Br2]dt = - 35 d[Br-]dt
AIPMT 2009
6

Half-life period of a first order reaction is 1386 s. The specific rate constant of the reaction is

  1. 0.5 10-2 s-1
  2. 0.5 10-3 s-1
  3. 5.0 10-2 s-1
  4. 5.0 10-3 s-1
AIPMT 2009
7

For the reaction A + B products, it is observed that (i) on doubling the initial concentration of A only, the rate of reaction is also doubled and (ii) on doubling the initial concentration of both A and B, there is a change by a factor of 8 in the rate of the reaction. The rate of this reaction is given by

  1. rate = k[A]2[B]2
  2. rate = k[A][B]2
  3. rate = k[A][B]
  4. rate = k[A]2[B]
AIPMT 2009
8

The rate constants k1 and k2 for two different reactions are 1016 e-2000/T and 1015 e-1000/T, respectively. The temperature at which k1 = k2 is

  1. 2000 K
  2. 10002.303 K
  3. 1000 K
  4. 20002.303 K
AIPMT 2008
9

The bromination of acetone that occurs in acid solution is represented by this equation. CH3COCH3(aq) + Br2(aq) CH3COCH2Br(aq) + H+(aq) + Br-(aq) These kinetic data were obtained for given reaction concentrations. array|c|c|c|c| [CH3COCH3], M & [Br2], M & [H+], M & Initial rate, disappearance of Br2, M s-1 \ 0.30 & 0.05 & 0.05 & 5.7 10-5 \ 0.30 & 0.10 & 0.05 & 5.7 10-5 \ 0.30 & 0.10 & 0.10 & 1.2 10-4 \ 0.40 & 0.05 & 0.20 & 3.1 10-4 \ array Based on these data, the rate equation is

  1. Rate = k[CH3COCH3][Br2][H+]2
  2. Rate = k[CH3COCH3][Br2][H+]
  3. Rate = k[CH3COCH3][H+]
  4. Rate = k[CH3COCH3][Br2]
AIPMT 2008
10

If 60% of a first order reaction was completed in 60 minutes, 50% of the same reaction would be completed in approximately (log 4 = 0.60, log 5 = 0.70)

  1. 45 minutes
  2. 60 minutes
  3. 40 minutes
  4. 50 minutes
AIPMT 2007
11

In a first-order reaction A B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is

  1. 2k
  2. 2k 0.5
  3. 2k
  4. 0.6930.5k
AIPMT 2007

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