Decomposition of H2O2 follows a first order reaction. In fifty m

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 Multiple Choice QuestionsShort Answer Type

301.

Following data are obtained for the reaction :
N2O5 → 2NO2 + ½O2

t/s 0 300 600
[N2O5]/mol L–1 1.6 × 10–2 0.8 × 10–2 0.4 × 10–2

(a) Show that it follows first order reaction.
(b) Calculate the half-life.
(Given log 2 = 0.3010 log 4 = 0.6021)

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302.

For the reaction,2N2O5 (g)   4 NO2 (g)  + O2 (g) the rate of formation of NO2 (g)  is 2.8 x 10-3 Ms-1. Calculate the rate of disappearance of N2O5 (g).


303.

A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction.

(Given: log 2 = 0.3010, log 4 = 0.6021, R = 8.314 JK–1 mol–1)


 Multiple Choice QuestionsMultiple Choice Questions

304.

Rate law for the reaction, A+ B → product is rate = k[A]2[B] What is the rate constant; if rate of reaction at a given temperature is 0.22 Ms-1, when [A]= 1 M band [BJ= 0.25 M?

  • 3.52 M-2s-1

  • 0.88  M-2s-1

  • 1.136  M-2s-1

  • 0.05  M-2s-1


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305.

Decomposition of H2O2 follows a first order reaction. In fifty minutes the concentration of H2O2 decreases from 0.5 to 0.125 M in one such decomposition. When the concentration of H2O2 reaches 0.05 M, the rate of formation of O2 will be:

  • 6.93×10−4 mol min−1

  • 2.66 L min−1 at STP

  • 1.34×10−2 mol min−1

  • 1.34×10−2 mol min−1


A.

6.93×10−4 mol min−1

For first order reaction



Alternative Method:
If fifty minutes, the concentration of H2O2 decreases from 0.5 to 0.125 M or in one half-life, concentration of H2O2 decreases from 0.5 to 0.25 M. In two half-lives, concentration of H2O2 decreases from 0.5 to 0.125 M or 2t1/2 = 50 min
t1/2 = 25 min
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306.

Higher order (>3) reactions are rare due to:

  • the increase in entropy and activation energy as more molecules are involved.

  • shifting of equilibrium towards reactants due to elastic collisions

  • loss of active species on a collision

  • loss of active species on a collision

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307.

The resistance of 0.2 M solution of an electrolyte is 50 Ω. The specific conductance of the solution of 0.5 M solution of the same electrolyte is 1.4 S m-1 and resistance of the same solution of the same electrolyte is 280 Ω. The molar conductivity of 0.5 M solution of the electrolyte in Sm-2 mol-1 is

  • 5 x 10-4

  • 5 x 10-3

  • 5 x 103

  • 5 x 103

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308.

For the non- stoichiometric reaction 2A + B → C + D, the following kinetic data were obtained in three separate experiment, all at 298 K.

  Initial concentration (A) Initial concnetration (B) Initial rate of formation of C (mol L-1 S-1)
1 0.1 M 0.1 M 1.2 x 10-3
2 0.1 M 0.2 M 1.2 x 10-3
3 0.2 M 0.1 M 2.4 x 10-3
 The rate law for the formation of C is
  • dC over dt space equals space straight k space left square bracket straight A right square bracket left square bracket straight B right square bracket
  • dC over dt space equals space straight k open square brackets straight A squared close square brackets left square bracket straight B right square bracket
  • dC over dt space equals space straight k left square bracket straight A right square bracket left square bracket straight B right square bracket squared
  • dC over dt space equals space straight k left square bracket straight A right square bracket left square bracket straight B right square bracket squared
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309.

The rate of a reaction doubles when its temperature changes from 300K to 310K. Activation energy of such a reaction will be (R = 8.314 JK–1 mol–1 and log 2 = 0.301)

  • 53.6 kJ mol-1

  • 48.6 kJ mol-1

  • 58.5 kJ mol-1

  • 58.5 kJ mol-1

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310.

For a first order reaction, (A) → products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is

  • 1.73 x 10–5 M/ min

  • 3.47 x 10–4 M/min

  • 3.47 x 10–5 M/min

  • 3.47 x 10–5 M/min

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