Chemical Kinetics PYQs

Match List I with List II: Choose the correct answer from the options given below :

For a certain reaction R → Product, the plot of concentration [R] versus time has a negative slope as shown. The order of reaction is:

Given the expression for the rate constant of a first-order reaction at temperature T(K): ln k = 14.34 − (1.25 × 10⁴)/T. The energy of activation in kcal mol⁻¹ is: (Given: k in s⁻¹, R = 1.987 cal mol⁻¹ K⁻¹)

If the half-life (t₁⁄₂) for a first order reaction is 1 minute, then the time required for 99.9% completion of the reaction is closest to: (1) 2 minutes (2) 4 minutes (3) 5 minutes (4) 10 minutes

For the reaction A(g) ⇌ 2B(g), the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500, at 1000 K. [Given : R = 0.0831 L atm mol⁻¹ K⁻¹] Kₚ for the reaction at 1000 K is

If the rate constant of a reaction is $0.03\ s^{-1}$, how much time does it take for $7.2\ mol\ L^{-1}$ concentration of reactant to get reduced to $0.9\ mol\ L^{-1}$? (Given: $\log 2 = 0.301$)

Activation energy of any chemical reaction can be calculated if one knows the value of:

Which plot of $\ln k$ vs $\dfrac{1}{T}$ is consistent with Arrhenius equation?

The rate of a reaction quadruples when temperature changes from 27°C to 57°C. Calculate the energy of activation. Given R = 8.314 J K⁻¹ mol⁻¹, log 4 = 0.6021

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R : Assertion A : A reaction can have zero activation energy. Reason R : The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to threshold value, is called activation energy. In the light of above statements, choose the correct answer from the options given below :

For a certain reaction, the rate = k[A]²[B], when the initial concentration of A is tripled keeping concentration of B constant, the initial rate would:

The given graph is a representation of kinetics of a reaction. The y and x axes for zero and first order reactions, respectively are:

For a first order reaction A → Products, initial concentration of A is 0.1 M, which becomes 0.001 M after 5 minutes. Rate constant for the reaction in min⁻¹ is:

For a reaction A → B, enthalpy of reaction is −4.2 kJ mol⁻¹ and enthalpy of activation is 9.6 kJ mol⁻¹. The correct potential energy profile for the reaction is shown in option:

The slope of Arrhenius plot (ln k vs 1/T) of first order reaction is −5 × $10^3$ K. The value of $E_a$ of the reaction is. Choose the correct option for your answer. [Given R = 8.314 J K⁻¹ mol⁻¹]

An increase in the concentration of the reactants of a reaction leads to change in

The rate constant for a first order reaction is 4.606 × 10⁻³ s⁻¹. The time required to reduce 2.0 g of the reactant to 0.2 g is:

A first order reaction has a rate constant of $2.303 \times 10^{-3}\ \text{s}^{-1}$. The time required for $40\ \text{g}$ of this reactant to reduce to $10\ \text{g}$ will be [Given that $\log_{10} 2 = 0.3010$]

For a reaction, activation energy $E_a = 0$ and the rate constant at $200\ \text{K}$ is $1.6 \times 10^6\ \text{s}^{-1}$. The rate constant at $400\ \text{K}$ will be given that gas constant, $R = 8.314\ \text{J K}^{-1}\text{mol}^{-1}$.

When initial concentration of the reactant is doubled, the half-life period of a zero order reaction

The correct difference between first and second order reactions is that

Which of the following statements is not correct?

Mechanism of a hypothetical reaction X₂ + Y₂ → 2XY is given below: (i) X₂ → X + X (fast) (ii) X + Y₂ ⇌ XY + Y (slow) (iii) X + Y → XY (fast) The overall order of the reaction will be

A first order reaction has a specific reaction rate of 10⁻² s⁻¹. How much time will it take for 20 g of the reactant to reduce to 5 g?

The decomposition of phosphine $(PH_3)$ on tungsten at low pressure is a first-order reaction. It is because:

The rate constant of the reaction $A \rightarrow B$ is 0.6 × 10⁻³ mole per second. If the concentration of A is 5 M, then concentration of B after 20 minutes is:

What is the activation energy for a reaction if its rate doubles when the temperature is raised from $20^\circ C$ to $35^\circ C$? $(R = 8.314\,J\,mol^{-1}K^{-1})$

A reaction having equal energies of activation for forward and reverse reactions has

Activation energy (Eₐ) and rate constants (k₁ and k₂) of a chemical reaction at two different temperatures (T₁ and T₂) related by :

The half life of a substance in a certain enzyme-catalysed reaction is 138 s. The time required for the concentration of the substance to fall from 1.28 mg L$^{-1}$ to 0.04 mg L$^{-1}$ is:

The rate of the reaction $$2N_2O_5 \rightarrow 4NO_2 + O_2$$ can be written in three ways: $$-\frac{d[N_2O_5]}{dt} = k[N_2O_5]$$ $$\frac{d[N_2O]}{dt} = k'[N_2O_5]$$ $$\frac{d[O_2]}{dt} = k''[N_2O_5]$$ The relationship between k and k' and between k and k'' are:

The unit of rate constant for a zero order reaction is:

The rate of reaction $$2NO + Cl_2 \rightarrow 2NOCl$$ is given by the rate equation $$\text{Rate} = k[NO]^2[Cl_2]$$ The value of the rate constant can be increased by :

For the reaction: $$\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}$$ If $$\frac{d[NH_3]}{dt} = 2 \times 10^{-4}\;mol\;L^{-1}\;s^{-1}$$ The value of $$-\frac{d[H_2]}{dt}$$ will be:

For the reaction $A + B \rightarrow$ products, it is observed that: (1) On doubling the initial concentration of $A$ only, the rate of reaction is also doubled. (2) 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 law of this reaction is:

In the reaction: $$\mathrm{BrO_3^- (aq) + 5Br^- (aq) + 6H^+ \rightarrow 3Br_2(l) + 3H_2O(l)}$$ The rate of appearance of bromine Br₂ is related to rate of disappearance of bromide ions as follows:

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

The bromination of acetone that occurs in acid solution is represented by the equation: $$CH₃COCH₃(aq) + Br₂(aq) → CH₃COCH₂Br(aq) + H⁺(aq) + Br⁻(aq)$$ These kinetic data were obtained for given reaction concentrations Based on these data, the rate equation is

The rate constants k₁ and k₂ for two different reactions are 10¹⁶ · e⁻²⁰⁰⁰ᐟᵀ and 10¹⁵ · e⁻¹⁰⁰⁰ᐟᵀ respectively. The temperature at which k₁ = k₂ is

Also find the value and unit of the rate constant from the data given above.

For the reaction 2A + B → 3C + D, which of the following does not express the reaction rate?

Consider the reaction N₂(g) + 3H₂(g) → 2NH₃(g). The equality relationship between (d[NH₃]/dt) and -(d[H₂]/dt) is:

For a first order reaction $A \rightarrow B$, the reaction rate at reactant concentration of $0.01\,M$ is found to be $2.0 \times 10^{-5}\,mol\,L^{-1}\,s^{-1}$. The half-life period of the reaction is:

The rate of reaction between two reactants $A$ and $B$ decreases by a factor of $4$, if the concentration of reactant $B$ is doubled. The order of this reaction with respect to reactant $B$ is: