**Chemical Kinetics**

**Questions: 2022**

- Derive the integrated rate equation for the first order reaction. Hence prove that half-life period is independent of initial concentration of the reactant. 3
- Time for half-life change for a first order reaction is 25 sec. Find the time taken for the completion of 99.9% reaction. 2
- Calculate the overall order of a reaction which has the rate expression of Rate =K[A]
^{1/2}[B]^{3/2}1 - The rate constant for a reaction of zero order in A is 0.0030 mol/L/sec. How long will it take for the initial concentration to fall from 0.10M to 0.075M? 2

**Questions: 2021**

- The inversion of cane sugar is represented by the reaction,

C_{12}H_{22}O_{11} + H_{2}O ———> C_{6}H_{12}O_{6} + C_{6}H_{12}O_{6}

- What is the order of this reaction? 1
- Give one condition that determines the order of this reaction. 1
- For zero order reaction, Rà P, derive the integrated rate equation and find its half-life time period. 3

**Questions: 2020**

- For a reaction, the first order rate constant at 600 K is 1.60 x 10
^{-5}S^{-1}. Its energy of activation is 209 kJ/mol. Calculate the rate constant of the reaction at 700 K. 2 - Define half-life period of a chemical reaction. 1
- What is the overall order of the reaction: CHCl
_{3}+ Cl_{2}→ CCl_{4 }+ HCl, with rate expression, r = k [CHCl_{3}][Cl_{2}]^{½}? Is this reaction an elementary reaction? Give reason. 2 - For first order reaction, prove that t
_{99% }=10 x t_{50%}or t_{99.99%}= 10 t_{½}2 - Write Arrhenius equation and indicate the terms involved. 1

**Questions:2019**

- When does the average rate of a reaction become equal to instantaneous rate? 1
- Write any one condition under which a bimolecular reaction may be kinetically of first order. 1
- Half-life period of a reaction increases with increase in initial concentration. Predict the order of the reaction. 1
- Decomposition of a compound follows first order kinetics. If it takes 15 minutes for 20% of original substance to decay, calculate –
- Rate constant
- The time at which 10% of the reactant remains undecayed. 2

**Questions: 2018**

- Calculate the overall order of a reaction which has the rate expression, r = k [A]
^{1/2}[B]^{3/2}.1 - What is the rate determining step of a reaction? 1
- What is the order of reaction whose rate constant has the same unit as the rate of reaction? 1
- Thermal decomposition of a compound is of first order. 50% decomposes in 120 minutes. How long will it take for 90% decompose? 2

**Questions: 2017**

- Write any tow differences between order and molecularity of a reaction. 2
- Write Arrhenius equation which relates the rate constant with temperature. 1
- A first order reaction takes 40 minutes for 30% decomposition. Calculate half-life. 2

**Questions: 2016**

- For first order reaction, it takes 5 minutes for the initial concentration of 0.6 mol /L to become 0.4 mol /L. How long will it take for the initial concentration to become 0.3 mol /L? 2
- Drive the integrated rate equation for the first order. Hence prove that half-life period for it is independent of initial concentration. 3

**Questions: 2015**

- Derive the general expression for the rate constant k for a first-order reaction. 2
- The initial concentration of N
_{2}O_{5}in the following first-order reaction

N_{2}O_{5} (g) ——→ 2NO_{2} (g) + ½O_{2} (g),

was 1.24 x 10^{-2} mol /L at 318 K. The concentration of N_{2}O_{5} after 60 minutes was 0.20 x 10^{-2} mol /L. Calculate the rate constant of the reaction at 318 K. 2

- Define pseudo first-order reaction. Give an example. 1
- The time required for 10% completion of a first-order reaction at 298 K is equal to that required for its 25% completion at 308 K. Calculate the energy of activation. 2
- What is meant by half-life period of a chemical reaction? Give the expression for half-life of a first-order Reaction. 2

**Questions: 2014**

- Prove that the time taken to complete 50% of a first-order reaction is independent of the initial concentration. 2
- Find the order of the reaction if the unit of rate constant k is mol
^{-½}L^{-½}s^{-1}. 1 - The rate constant of a reaction is 1.5 x 10
^{7}s^{-1}at 50°C and 4.5 x 10^{7}s^{-1}at 100°C. Calculate the activation energy, E_{a}for the reaction. (R=8.314J/K/mol) 2

**Questions: 2013**

- In a chemical reaction, a catalyst (alters the amount of the products, decreases the ΔH of forward reaction, lower the activation energy, increases the ΔH of forward reaction). ½
- In a reaction, 2A —→ Products, the concentration of A decreases from 0.5 mol/L to 0.4 mol/L in 10 minutes. Calculate the rate during this interval. 2
- The initial concentration of N
_{2}O_{5}in the following first-order reaction

N_{2}O_{5} (g) ——→ 2NO_{2} (g) + ½O_{2} (g),

was 1.24 x 10^{-2} mol /L at 318 K. The concentration of N_{2}O_{5} after 60 minutes was 0.20 x 10^{-2} mol /L. Calculate the rate constant of the reaction at 318 K. 2

**Questions: 2012**

- At 298 K, the specific conductance of a 0.01M solution of acetic acid in water is 1.65 x 10
^{-4}ohm^{-1}cm^{-1}. Calculate the molar conductance of the solution. 1 - The rate constants of a reaction at 500K and 700K are 0.02 s
^{-1}and 0.07 s^{-1}Calculate the value of E_{a}and A. (R=8.314J/K/mol). 3 - Calculate the t½ for a zero-order reaction. 1
- What is the order of reaction if its unit of rate constant, k is (i) S
^{-1}& (ii) moles/L/s? 1

**Questions: 2011**

- Mention any four factors that influence the rate of a chemical reaction. 2
- Decomposition of a compound follows first-order kinetics. If it takes 15 minutes for 20 % of original substance to decay, calculate (a) the specific rate constant, (b) the tome at which 10% of the reactant remains unreacted and (c) the half-life of the reaction. 3

**Questions: 2010**

- Time for half-change for a first-order reaction is 25 seconds. Find the time taken for the completion of 99% reaction. 2
- State Arrhenius equation on the temperature dependence of reaction rate. The slope of line with graph of log k versus 1/T is – 584 J. Find E
_{a}. [R=8.314J/K/mol] 2 - Which step is the rate determining step in a reaction and why? 1

**Questions: 2009**

- Why the rate of a reaction does not remain constant throughout a chemical reaction? 1
- Derive the integrated rate equation of a first-order reaction. 2
- State a condition under which a bimolecular reaction may be kinetically first order. 1
- In some cases, it is found that a large number of colliding molecules have energy more than threshold value, yet the reaction is found to be very slow, why? 1

**Questions: 2008**

- What is the overall order of the reaction: CHCl
_{3}+ Cl_{2 }→ CCl_{4}+ HCl, with rate expression, r = k [CHCl_{3}][Cl_{2}]^{½}? Is this reaction an elementary reaction? Give reason. 2 - State Arrhenius equation and indicate the terms involved. Will the rate constant of any reaction depend upon temperature if the activation energy is zero? 3
- The first-order rate constant for the decomposition of ethyl iodide by the reaction

C2H_{5}I (g) → C_{2}H_{4} (g) + HI

at 600 K is 1.60 x 10^{-5} S^{-1}. Its energy of activation is 209 kj/mol. Calculate the rate constant of the reaction at 700 K. 2

- The rate of a reaction cannot be determined by dividing the total change in concentration of the reactants by the total time taken for bringing about the change. Why? 1

**Questions: 2007**

- A reaction is 50% complete in 2 hours and 75% complete in 4 hours. What is the order of the reaction? 1

**Questions: 2006**

- Why rate of a reaction does not remain constant throughout? 1
- When does rate of the reaction become equal to specific reaction rate? 1
- Write Arrhenius equation. 1
- A first order reaction has a specific reaction rate of 2.31 x 10-3 Sec-1. Calculate the half-life period of the reaction. 1

**Questions: 2005**

- What is the order of a reaction, whose rate remains constant with the progress of the reaction? 1
- What is the effect of temperature on the rate of a reaction? 1
- Prove that the time taken to complete 50% of a first-order reaction is independent of the initial concentration. 2

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