Chemical Kinetics · Chemistry · COMEDK
MCQ (Single Correct Answer)
The initial pressure of the system before decomposition for a first order gas phase reaction $A_{(g)} \rightarrow B_{(g)}+C_{(g)}$ was $\mathrm{P}_{\mathrm{i}}$. After lapse of time ' t ', total pressure of the system increased by ' x ' units and became $\mathrm{P}_{\mathrm{t}}$. The rate constant ' k ' for the reaction is given as:
A first order reaction is $50 \%$ complete in 30 minutes at 300 K and in 10 minutes at 320 K . The activation energy of the reaction ( $E_a$ ) is: $\left[R=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} ; \log 2=0.3010 ; \log 3=0.4771\right]$
Which of the following factors is altered by the addition of a catalyst during a chemical reaction?
In the synthesis of $\mathrm{NH}_3$ from $\mathrm{H}_2$ and $\mathrm{N}_2$, if $6 \times 10^{-2}$ mole of hydrogen disappears in 10 minutes, the number of moles of $\mathrm{NH}_3$ formed in 0.3 minutes is:
$$ \text { When the concentration of the reactant in a given reaction is halved and if the rate of reaction is halved, the order of the reaction is: } $$
The rate constants for two different reactions, $\mathrm{k}_1$ and $\mathrm{k}_2$ are $10^{16} \cdot \mathrm{e}^{-2000 / \mathrm{T}}$ and $10^{15} \cdot \mathrm{e}^{-1000 / \mathrm{T}}$ respectively. The temperature at which $k_1=k_2$ is
Rate law can be determined from a balanced chemical equation if
$60 \%$ of a first order reaction was completed in 60 min , then $50 \%$ of the same reaction can be completed in: $[\log 4=0.60, \log 5=0.69]$
Identify the correct values to be plotted in the graph, the slope of which can be used to determine the activation energy of a reaction.
When the initial concentration of a zero order reaction is doubled, the half-life of the reaction is:
(i) and (ii) are 2 chemical reactions carried out at TK.
(i). $\mathrm{X} \rightarrow \mathrm{Y}+\mathrm{W}$ with $\mathrm{k}_1$ as rate constant.
(ii). $\mathrm{X} \rightarrow \mathrm{Z}+\mathrm{W}$ with $k_2$ as rate constant.
The Activation energy for reaction (ii) is 3 times that of reaction (i). What is the expression for $k_1$ ?
Two statements, One Assertion (A) and the other Reason (R) are given. Choose the right option.
Assertion: The rate constant $(\mathrm{k})$ for a chemical reaction gets nearly doubled for a $10^0$ rise in temperature.
Reason: The number of bimolecular collisions between reactant molecules increase with increase in temperature
The following results were obtained during study of the reaction $2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g}) \rightarrow 2 \mathrm{NOCl}(\mathrm{g})$. Determine the value of $[\mathrm{X}]$ in $\mathrm{mol} / \mathrm{L}$
| Experiment | [NO] mol / L |
[Cl$_2$] mol / L |
Initial rate of formation. [NOCl] mol / L / min |
|---|---|---|---|
| I | 0.2 | 0.2 | $6.0 \times 10^{-3}$ |
| II | 0.2 | 0.4 | $2.4 \times 10^{-2}$ |
| III | 0.4 | 0.2 | $1.2 \times 10^{-2}$ |
| IV | X | 0.6 | $1.35 \times 10^{-1}$ |
For a given reaction, ,$$\mathrm{X}(\mathrm{g})+\mathrm{Y}(\mathrm{g} \rightarrow \mathrm{Z}(\mathrm{g})$$, the order of reaction with respect to $$\mathrm{X}$$ and $$\mathrm{Y}$$ are $$\mathrm{m}$$ and $$\mathrm{n}$$ respectively. If the concentration of $$\mathrm{X}$$ is tripled and that of $$\mathrm{Y}$$ is decreased to one third, what is the ratio between the new rate to the original rate of the reaction?
For a reaction $$5 X+Y \rightarrow 3 Z$$, the rate of formation of $$Z$$ is $$2.4 \times 10^{-5} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ Calculate the average rate of disappearance of $$\mathrm{X}$$.
In the presence of a catalyst at a given temperature of $$27^{\circ} \mathrm{C}$$, the Activation energy of a specific reaction is reduced by $$100 \mathrm{~J} / \mathrm{mol}$$. What is the ratio between the rate constants for the catalysed $$(\mathrm{k}_2)$$ and uncatalysed $$(\mathrm{k}_1)$$ reactions?
The following data was recorded for the decomposition of XY compound at 750K
| [XY] mol / L | Rate of decomposition of XY mol / L s |
|---|---|
| 0.4 | $$5.5\times10^{-7}$$ |
| 0.8 | $$22.0\times10^{-7}$$ |
| 1.2 | $$49.5\times10^{-7}$$ |
What is the order of reaction with respect to decomposition of XY?
The Activation energy for the reaction $$A \rightarrow B+C$$, at a temperature $$\mathrm{TK}$$ was $$0.04606 \mathrm{~RT} \mathrm{~J} / \mathrm{mol}$$. What is the ratio of Arrhenius factor to the Rate constant for this reaction?
The temperature $$(\mathrm{T})$$ and rate constant $$(\mathrm{k})$$ for a first order reaction $$\mathrm{R} \rightarrow \mathrm{P}$$, was found to follow the equation $$\log \mathrm{k}=-(2000) \frac{1}{\mathrm{~T}}+8.0$$. The pre-exponential factor '$$\mathrm{A}$$' and activation energy $$\mathrm{E}_{\mathrm{a}}$$, respectively are: [Given: $$\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$]
Given below a first order reaction in the gas phase
$$\mathrm{A}(\mathrm{g}) \rightarrow \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$$
If the initial pressure of the system is $$\mathrm{P}_{\mathrm{i}}$$ and the total pressure at $$\mathrm{t}$$ seconds is $$\mathrm{P}_{\mathrm{t}}$$, the rate constant $$\mathrm{k}$$ for the reaction is:
For the reaction, $$\mathrm{A}+3 \mathrm{~B} \rightarrow 2 \mathrm{C}+\mathrm{D}$$, the concentration of $$\mathrm{A}$$ changes from 0.0150 to 0.0125 in 1 minute. The rate of formation of $$\mathrm{C}$$ in $$\mathrm{mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ is:
The rate of appearance of bromine is related to the disappearance of bromide ion in the equation given below is:
$$\mathrm{BrO}_3^{-} \text {(aq) }+5 \mathrm{Br}^{-} \text {(aq) }+6 \mathrm{H}^{+} \rightarrow 3 \mathrm{Br}_2(\mathrm{l})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$$
The half-life for a zero order reaction is
The time required for $$80 \%$$ of a first order reaction is "$$y$$" times the half-life period of the same reaction. What is the value of "$$y$$"?
The rate constant for the reaction $$\mathrm{A} \rightarrow \mathrm{B}+\mathrm{C}$$ at $$500 \mathrm{~K}$$ is given as $$0.004 \mathrm{~s}^{-1}$$. At what temperature will the rate constant become $$0.014 \mathrm{~s}^{-1}$$ ? $$\mathrm{E}_{\mathrm{a}}$$ for the reaction is $$18.231 \mathrm{~kJ}$$.
For the reaction $$\mathrm{Cl}_{2(\mathrm{~g})}+2 \mathrm{NO}_{(\mathrm{g})} \rightarrow 2 \mathrm{NOCl}_{(\mathrm{g})}$$, the following data was obtained:
| Experiment No. | Initial concentration of $$\mathrm{Cl_2}$$ ($$\mathrm{M}$$) | Initial concentration of $$\mathrm{NO}$$ ($$\mathrm{M}$$) | Initial reaction rate ($$\mathrm{M}$$/min) |
|---|---|---|---|
| I | 0.15 | 0.15 | 0.60 |
| II | 0.30 | 0.15 | 1.20 |
| III | 0.15 | 0.3 | 2.40 |
| IV | 0.25 | 0.25 | 2.78 |
Identify the order of the reaction with respect to $$\mathrm{Cl}_2, \mathrm{NO}$$ and the value of Rate constant.
Given below are 4 graphs [A], [B], [C] and [D]
Identify the 2 graphs that represent a Zero order reaction?
A given chemical reaction is represented by the following stoichiometric equation.
$$3 X+2 Y+\frac{5}{2} Z \rightarrow P_1+P_2+P_3$$
The rate of reaction can be expressed as _________.
How much faster would a reaction proceed at $$25^{\circ} \mathrm{C}$$ than at $$0^{\circ} \mathrm{C}$$ if the activation energy is $$65 \mathrm{~kJ}$$?
At $$300 \mathrm{~K}$$, the half-life period of a gaseous reaction at an initial pressure of $$40 \mathrm{~kPa}$$ is 350 s. When pressure is $$20 \mathrm{~kPa}$$, the half-life period is 175 s. What is the order of the reaction?
For a reaction, $$2 A+B \longrightarrow$$ products, If concentration of $$B$$ is kept constant and concentration of $$A$$ is doubled then rate of reaction is
A first order reaction proceeds to $$90 \%$$ completion. What will be the approximate time taken for $$90 \%$$ completion in relation to $$t_{1 / 2}$$ of the reaction?
For a reaction of the type, $$2 \mathrm{X}+\mathrm{Y} \rightarrow \mathrm{A}+\mathrm{B}$$, the following is the data collected:
| Experiment | $$\mathrm{[X]}$$ | $$\mathrm{[Y]}$$ | Initial rate of formation of A |
|---|---|---|---|
| 1 | 0.2 | 0.2 | $$12.0\times10^{-3}$$ |
| 2 | 0.6 | 0.4 | $$\mathrm{14.4\times10^{-2}}$$ |
| 3 | 0.6 | 0.8 | $$5.76\times10^{-1}$$ |
| 4. | 0.8 | 0.2 | $$\mathrm{4.8\times10^{-2}}$$ |
What is the overall order of the reaction?
Match the details given in Column I with those given in Column II
| S.No. | Column I | S.No. | Column II |
|---|---|---|---|
| A | For complex reactions order is determined by | P | Rate of reaction. |
| B | For Zero order reaction unit of $\mathrm{k}$ is same as that of | Q | Slope $$=k/2.303$$ |
| C | Mathematical expression which gives relationship between rate of reaction and concentrations of reactants is called | R | Slowest rate determining step. |
| D | For a first order reaction plot of $$\mathrm{\log \left[R_0\right] /[R]}$$ vs time gives | S | Rate law. |
Given below are graphs showing the variation in velocity constant with temperature on Kelvin scale. Identify the graph which represents Arrhenius equation.
The rate constant for a First order reaction at $$560 \mathrm{~K}$$ is $$1.5 \times 10^{-6}$$ per second. If the reaction is allowed to take place for 20 hours, what percentage of the initial concentration would have converted to products?
A newly prepared radioactive nuclide has a decay constant of 6.93 s$$^{-1}$$. What is the half-life of the nuclide?
Which of the following statement is incorrect about activation energy?
For the reaction 2N$$_2$$O$$_5$$ $$\to$$ 4NO$$_2$$ + O$$_2$$.
If initial pressure is 100 atm and rate constant $$k$$ is 3.38 $$\times$$ 10$$^{-5}$$ s$$^{-1}$$. after 20 min the final pressure of N$$_2$$O$$_5$$ will be
Determine the specific rate constant of the reaction. If the half-life period of a first order reaction is 1402 s.
Rate constant (K) of a reaction has least value at
For the reaction 2N$$_2$$O$$_5$$ $$\to$$ 4NO$$_2$$ + O$$_2$$, rate constant $$k$$ is 4.48 $$\times$$ 10$$^{-5}$$ s$$^{-1}$$ and the initial pressure is 600 atm. After 10 min, determine the final pressure of N$$_2$$O$$_5$$.
Which one of the following is a second order reaction?