Chemical Kinetics — JEE Main PYQs

At $30^{\circ }\mathrm{C}$, the half life for the decomposition of ${\mathrm{AB}}_2$ is 200 s and is independent of the initial concentration of ${\mathrm{AB}}_2$. The time required for $80\%$ of the ${\mathrm{AB}}_2$ to decompose is (Given: $\log 2=0.30$; $\log 3=0.48$)

[A] → [B]
Reactant Product

If formation of compound [B] follows the first order of kinetics and after 70 minutes the concentration of $[\mathrm{A}]$ was found to be half of its initial concentration. Then the rate constant of the reaction is …

For the decomposition of azomethane.
${\mathrm{CH}}_3{\mathrm{N}}_2{\mathrm{CH}}_3(\mathrm{g})\to {\mathrm{CH}}_3{\mathrm{CH}}_3(\mathrm{g})+{\mathrm{N}}_2(\mathrm{g})$ a first order reaction, the variation in partial pressure with time at 600 K is given as

The …

For a reaction $\mathrm{A}\to 2\mathrm{B}+\mathrm{C}$ the half lives are 100 s and 50 s when the concentration of reactant A is 0.5 and $1.0{\mathrm{mol}\mathrm{L}}^{-1}$ respectively. The order of the reaction is ______.
(Nearest Integer)

A radioactive element has a half life of 200 days. The percentage of original activity remaining after 83 days is ______. (Nearest integer)
(Given : antilog $0.125=1.333$, antilog $0.693=4.93$)

It has been found that for a chemical reaction with rise in temperature by 9 K the rate constant gets doubled. Assuming a reaction to be occurring at 300 K, the value of activation energy is found to be ______ ${\mathrm{kJ}\mathrm{mol}}^{-1}$. [nearest integer]
(Given $\ln 10=2.3$, …

For a first order reaction $\mathrm{A}\to \mathrm{B}$, the rate constant, $\mathrm{k}=5.5\times 10^{-14}{\mathrm{s}}^{-1}$. The time required for $67\%$ completion of reaction is $\mathrm{x}\times 10^{-1}$ times the half life of reaction. The value of $x$ is ______.
(N …

The equation
$\mathrm{k}=\left(6.5\times 10^{12}{\mathrm{s}}^{-1}\right){\mathrm{e}}^{-26000\mathrm{K}/\mathrm{T}}$
is followed for the decomposition of compound A .
The activation energy for the reaction is ____ kJ ${\mathrm{mol}}^{-1}$. [nearest integer]
(Given: …

Catalyst A reduces the activation energy for a reaction by $10\mathrm{kJ}{\mathrm{mol}}^{-1}$ at 300 K. The ratio of rate constants, $\frac{k_{\mathrm{T},\text{Catalysed}}}{k_{\mathrm{T},\text{Uncatalysed}}}$ is ${\mathrm{e}}^{\mathrm{x}}$. The value of x is $\_\_\_\_$. [neares …

The activation energy of one of the reactions in a biochemical process is $532611{\mathrm{J}\mathrm{mol}}^{-1}$. When the temperature falls from 310 K to 300 K, the change in rate constant observed is ${\mathrm{k}}_{300}=\mathrm{x}\times 10^{-3}{\mathrm{k}}_{310}$. The value of x is
[Given: …

A flask is filled with equal moles of A and B. The half lives of A and B are 100 s and 50 s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is
____ s.
(Given $:\ln 2=0.693$ )

The rate constant for a first order reaction is given by the following equation:
$\ln \mathrm{k}=33.24-\frac{2.0\times 10^4\mathrm{K}}{\mathrm{T}}$
The Activation energy for the reaction is given by
____ $\mathrm{kJ}{\mathrm{mol}}^{-1}$. (In Nearest integer)
(Given: …

The reaction between X and Y is first order with respect to X and zero order with respect to Y.
| Experiment | [X] mol L${}^{-1}$ | [Y] mol L${}^{-1}$ | Initial rate mol L${}^{-1}$ min${}^{-1}$ ||------------|------------------|------------------|--------------------------------------- …

The rate constants for decomposition of acetaldehyde have been measured over the temperature range 700-1000 K. The data has been analysed by plotting ln k vs 10³/T graph. The value of activation energy for the reaction is ______ kJ mol⁻¹. (Nearest integer) (Given: R = 8.31 J K⁻¹ …

For a first order reaction, the time required for completion of $90\%$ reaction is '$x$' times the half life of the reaction. The value of '$x$' is
(Given: $\ln 10=2.303$ and $\log 2=0.3010$ )

At 345 K, the half life for the decomposition of a sample of a gaseous compound initially at 55.5 kPa was 340 s. When the pressure was 27.8 kPa, the half life was found to be 170 s. The order of the reaction is $\_\_\_\_$. [integer answer]

For a given chemical reaction


Concentration of C changes from 10 mmol ${\mathrm{dm}}^{-3}$ to $20\mathrm{mmol}{\mathrm{dm}}^{-3}$ in 10 seconds. Rate of appearance of …

Gaseous cyclobutene isomerizes to butadiene in a first order process which has a 'k' value of $3.3\times 10^{-4}{\mathrm{s}}^{-1}$ at $153^{\circ }\mathrm{C}$. The time in minutes it takes for the isomerization to proceed 40% to completion at this temperature is ____. (Rounde …

The following data was obtained for chemical reaction given below at 975 K .

\begin{tabular}{lclc}
& $2{\mathrm{NO}}_{(\mathrm{g})}+$ & $2{\mathrm{H}}_{2(\mathrm{g})}\to$ & ${\mathrm{N}}_{2(\mathrm{g})}+2{\mathrm{H}}_2{\mathrm{O}}_{(\mathrm{g})}$ \\
& {$[\mathrm{NO}]$} & { …

The reaction rate for the reaction
${\left[{\mathrm{PtCl}}_4\right]}^{2-}+{\mathrm{H}}_2\mathrm{O}\rightleftharpoons {\left[\mathrm{Pt}\left({\mathrm{H}}_2\mathrm{O}\right){\mathrm{Cl}}_3\right]}^{-}+{\mathrm{Cl}}^{-}$
was measured as a function of concentrations of different specie …

The inactivation rate of a viral preparation in proportional to the amount of virus. In the first minute after preparation, $10\%$ of the virus is inactivated. The rate constant for viral inactivation is ____ $\times 10^{-3}{\min }^{-1}$. (Nearest integer)
[ Use: …

Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half- life of 3.33 h at $25^{\circ }\mathrm{C}$. After 9 h , the fraction of sucrose remaining is f . The value of ${\log }_{10}\left(\frac{1}{\mathrm{f}}\right)$ is $\_\_\_\_$ …

${\mathrm{PCl}}_5(\mathrm{g})\to {\mathrm{PCl}}_3(\mathrm{g})+{\mathrm{Cl}}_2(\mathrm{g})$
In the above first order reaction, the concentration of ${\mathrm{PCl}}_5$ reduces from initial concentration $50\mathrm{mol}{\mathrm{L}}^{-1}$ to …

The first order rate constant for the decomposition of ${\mathrm{CaCO}}_3$ at 700 K is $6.36\times 10^{-3}{\mathrm{s}}^{-1}$ and activation energy is $209\mathrm{kJ}{\mathrm{mol}}^{-1}$. Its rate constant (in ${\mathrm{s}}^{-1}$) at 600 K is $x\times 10^{-6}$. The value of x is …

For the reaction $\mathrm{aA}+\mathrm{bB}\to \mathrm{cC}+\mathrm{dD}$, the plot of $\log \mathrm{K}$ vs $\frac{1}{\mathrm{T}}$ is given below :
The temperature at which the rate constant of the reaction is $10^{-4}{\mathrm{s}}^{-1}$ is ____ K.
(Rounded - off …

${\mathrm{N}}_2{\mathrm{O}}_{5(\mathrm{g})}\to 2{\mathrm{NO}}_{2(\mathrm{g})}+\frac{1}{2}{\mathrm{O}}_{2(\mathrm{g})}$

In the above first order reaction the initial concentration of ${\mathrm{N}}_2{\mathrm{O}}_5$ is $2.40\times 10^{-2}\mathrm{mol}{\mathrm{L}}^{-1}$ a …

An exothermic reaction $\mathrm{X}\to \mathrm{Y}$ has an activation energy $30\mathrm{kJ}{\mathrm{mol}}^{-1}$. If energy change $\Delta \mathrm{E}$ during the reaction is $-20\mathrm{kJ}$, then the activation energy for the reverse reaction in kJ is ______ (Integer a …

The reaction that occurs in a breath analyser, a device used to determine the alcohol level in a person's blood stream is …

If the activation energy of a reaction is $80.9\mathrm{kJ}{\mathrm{mol}}^{-1}$, the fraction of molecules at 700 K, having enough energy to react to form products is $e^{-x}$. The value of $x$ is ____ (Rounded-off to the nearest integer).
[use …

For the reaction $\mathrm{A}\to \mathrm{B}$, the rate constant $\mathrm{K}$ (in ${\mathrm{s}}^{-1}$) is given by

The energy of activation in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ is ______. (Nea …

For a first order reaction, the ratio of the time for $75\%$ completion of a reaction to the time for 50% completion is ____ . (Integer answer)

For a reaction of order n, the unit of the rate constant is:

For a certain first order reaction $32\%$ of the reactant is left after 570 s . The rate constant of this reaction is ____ $\times 10^{-3}{\mathrm{s}}^{-1}$. (Round off to the nearest integer).
[Given : ${\log }_{10}2=0.301,\ln 10=2.303$ ]

For the following graphs,

For the first order reaction $\mathrm{A}\to 2\mathrm{B}$, 1 mole of reactant A gives 0.2 moles of B after 100 minutes. The half life of the reaction is $\_\_\_\_$ min. (Round off to the Nearest Integer).
[Use : $\ln 2=0.69,\ln 10=2.3$ Properties of logarithms : …

Which one of the following given graphs represents the variation of rate constant (k) with temperature (T) for an endothermic reaction?

The decomposition of formic acid on gold surface follows first order kinetics. If the rate constant at 300 K is $1.0\times 10^{-3}{\mathrm{s}}^{-1}$ and the activation energy ${\mathrm{E}}_a=11.488\mathrm{kJ}{\mathrm{mol}}^{-1}$, the rate constant at 200 K is ____ …

A and B decompose via first order kinetics with half-lives 54.0 min and 18.0 min respectively. Starting from an equimolar non reactive mixture of A and B, the time taken for the concentration of $A$ to become 16 times that of $B$ is ______ min.
(Round off to the nearest integ …

A reaction has a half life of 1 min. The time required for $99.9\%$ completion of the reaction is ______ min. (Round off to the nearest integer).
[Use $\ln 2=0.69;\ln 10=2.3$]

The reaction $2\mathrm{A}+{\mathrm{B}}_2\to 2\mathrm{AB}$ is an elementary reaction.
For a certain quantity of reactants, if the volume of the reaction vessel is reduced by a factor of 3, the rate of reaction increases by a factor of ______.
(Round off to the nearest …

$2\mathrm{NO}(\mathrm{g})+{\mathrm{Cl}}_2(\mathrm{g})\rightleftharpoons 2\mathrm{NOCl}(\mathrm{s})$
This reaction was studied at $-10^{\circ }\mathrm{C}$ and the following data was obtained

\begin{tabular}{llll}
run & {$[\mathrm{NO}{]}_0$} & { …

For a chemical reaction A → B, it was found that concentration of B is increased by 0.2 mol L⁻¹ in 30 min. The average rate of the reaction is ______ × 10⁻¹ mol L⁻¹ h⁻¹. (in nearest integer)

During the nuclear explosion, one of the product of ${}^{90}\mathrm{Sr}$ with half life of 6.93 years. If 1 $\mu \mathrm{g}$ of ${}^{90}\mathrm{Sr}$ absorbed in the bones of newly born baby in place of Ca, how much time, in years is required to reduce it by $90\%$ if …

For the reaction
$2{\mathrm{H}}_2(\mathrm{g})+2\mathrm{NO}(\mathrm{g})⟶{\mathrm{N}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}$, the observed rate expression is, rate $={\mathrm{k}}_{\mathrm{f}}[\mathrm{NO}{]}^2\left[{\mathrm{H}}_2\right]$. The rate expression f …

The rate of a certain biochemical reaction at physiological temperature (T) occurs $10^6$ times faster with enzyme than without. The change in the activation energy upon adding enzyme is :

Consider the following plots of rate constant versus $\frac{1}{\mathrm{T}}$ for four different reactions. Which of the following order is correct for the activation energies of these reactions?

A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The activation energy (in $\mathrm{kJ}/\mathrm{mol}$) for this process is closest to ____

(Given, …

For following reactions
$\mathrm{A}\stackrel{700\mathrm{K}}{\to }$ Product
A $\underset{\text{catalyst}}{\overset{500\mathrm{K}}{\to }}$ Product
it was found that the ${\mathrm{E}}_{\mathrm{a}}$ is decreased by $30kJ/mol$ in the presence of catalyst. If the rate remains unc …

The rate constant (k) of a reaction is measured at different temperatures (T), and the data are plotted in the given figure. The activation energy of the reaction in kJ ${\mathrm{mol}}^{-1}$ is: ( $R$ is gas constant)

It is true that: