Chemical Kinetics

The branch of chemistry which deals with the study of reaction rates and their mechanisms is called:

In a reaction $R \rightarrow P$, if the concentration of $R$ changes from $0.03\text{M}$ to $0.02\text{M}$ in $25\text{ minutes}$, the average rate in $\text{mol L}^{-1} \text{min}^{-1}$ is:

When the concentration of reactants is expressed in atmospheres (atm), what is the unit for the average rate of reaction?

For the reaction $1/2 O_2 + 2Cu \rightarrow 2CuO$, the rate of consumption of $O_2$ is how many times the rate of the reaction?

The temperature coefficient of a reaction is usually found to lie between:

In the reaction $2A + B \rightarrow C$, if the concentration of $A$ is tripled and $B$ is doubled, and the rate equation is $Rate = k[A][B]^2$, the rate will increase by a factor of:

Which of the following statements about the rate of reaction is FALSE?

For a reaction $A + B \rightarrow C$, the rate is $k[A][B]$. If the concentration of $A$ is kept constant and the concentration of $B$ is doubled, how does the rate of disappearance of $A$ change?

For a gaseous reaction $2A \rightarrow 4B + C$, if the pressure of $A$ drops by $20\ mmHg$ in $10\ minutes$, what is the average rate of the reaction in $mmHg\ min^{-1}$?

In a reaction $3A \rightarrow 2B$, the rate of disappearance of $A$ ($r_A$) and the rate of appearance of $B$ ($r_B$) are related as:

Which of the following is the correct Arrhenius equation?

The 'Orientation Factor' in collision theory is denoted by the letter:

For a first-order reaction, the units of the frequency factor $A$ in the Arrhenius equation are:

Generally, as the complexity of the reactant molecules increases, the reaction rate:

Which of the following would NOT increase the rate of reaction between zinc and sulfuric acid?

An endothermic reaction $A \rightarrow B$ has an activation energy of $15 kJ/mol$. If the energy of reaction $\Delta H$ is $5 kJ/mol$, what is the activation energy for the reverse reaction $B \rightarrow A$?

According to the Arrhenius theory, why does the rate constant $k$ increase with temperature?

In which case will the rate of a heterogeneous reaction $Solid + Gas \to Product$ increase the most?

If the slope of a $\log_{10} k$ vs $1/T$ plot is $-1000 K$, what is the activation energy $E_a$ in $cal/mol$? (Use $R = 2 cal \cdot K^{-1} \cdot mol^{-1}$)

Which of the following statements is TRUE about the 'Activated Complex'?

Which order of reaction does the following unit of rate constant $k$ belong to: $L\ mol^{-1}\ s^{-1}$?

What is the dimension of the rate constant $k$ for a first-order reaction?

The time required for 90% completion of a first-order reaction ($t_{90\%}$) is approximately how many times the half-life ($t_{1/2}$)?

In the decomposition of $N_2O_5$ (a first-order reaction), if the initial concentration is $1.24 \times 10^{-2}\ mol\ L^{-1}$ and the concentration after $60\ minutes$ is $0.62 \times 10^{-2}\ mol\ L^{-1}$, what is the half-life?

If the rate constant $k$ for a first-order reaction is $2.0 \times 10^{-2}\ \text{min}^{-1}$, what is the half-life of the reaction?

In a first-order reaction, the ratio of time required for $87.5\%$ completion to its half-life is:

For a first-order reaction, if we plot $\log[R]$ vs $t$, the slope of the line is $-2.0 \times 10^{-4}\ \text{s}^{-1}$. The rate constant $k$ for the reaction is:

A first-order gas phase reaction $A(g) \rightarrow B(g) + 2C(g)$ has an initial pressure $P_i$. If the total pressure at time $t$ is $P_t$, the partial pressure of $A$ at time $t$ is:

For a first-order reaction $A \rightarrow B$, the time for $93.75\%$ completion is $x$ minutes. The time for $50\%$ completion in terms of $x$ is:

If a zero-order reaction has a rate constant of $2 \times 10^{-2} \text{ mol L}^{-1} \text{s}^{-1}$ and the initial concentration is $1.0 \text{ M}$, the concentration after $1$ minute is:

The Arrhenius equation was proposed to explain the effect of temperature on the:

Which constant is used to calculate the value of $E_a$ when two rate constants at two different temperatures are known?

The energy barrier that reactants must overcome to form products is called:

In the Arrhenius equation $k = A e^{-E_a/RT}$, if $E_a$ is positive, then as $T$ increases, the term $e^{-E_a/RT}$ will:

Two chemical reactions, 1 and 2, follow the Arrhenius equation which can be expressed in the form $\ln k = \ln A - \frac{E_a}{RT}$. The specific parameters for these reactions are provided in the diagram below. At what temperature $T$ (in Kelvin) will the rate constants of both reactions be identical ($k_1 = k_2$)?

According to the Arrhenius equation, if the temperature is doubled (from $T$ to $2T$), the new rate constant $k'$ is related to the original $k$ by:

A reaction has a rate constant of $1.2 \times 10^{-3} \text{ s}^{-1}$ at $300\text{ K}$. If the activation energy is $0$ (theoretically), what is the rate constant at $400\text{ K}$?

A certain reactant $A$ decomposes into two products $B$ and $C$ via two independent first-order parallel pathways. The rate constants for these pathways are $k_B$ and $k_C$ respectively. A plot of $\ln(k_B/k_C)$ vs $1/T$ results in a straight line with a slope of $+2405.5\text{ K}$. If the activation energy for the pathway leading to product $C$ ($E_{a,C}$) is $120\text{ kJ mol}^{-1}$, calculate the activation energy for the pathway leading to product $B$ ($E_{a,B}$). (Given: $R = 8.314\text{ J K}^{-1}\text{ mol}^{-1}$)

A reaction takes place in two steps with activation energies $E_{a1} = 180\text{ kJ/mol}$ and $E_{a2} = 80\text{ kJ/mol}$. If the first step is the rate-determining step, the activation energy of the overall reaction is approximately:

For two reactions $1$ and $2$, $A_1 = A_2$ and $E_{a1} > E_{a2}$. If $k_1$ and $k_2$ are their rate constants at temperature $T$, then:

What is the primary factor that causes the rate to increase significantly with a small rise in temperature?

How does the steric factor $P$ relate to the probability of an effective collision?

In collision theory, $E_a$ stands for:

Which of the following is essential for a reaction according to collision theory?

Which of the following factors does NOT affect the collision frequency $Z_{AB}$ in a gas-phase reaction?

The concept of 'threshold energy' is most closely associated with which requirement of the collision theory?

Collision theory can be related to the kinetic theory of gases. The kinetic energy of a molecule is given by $1/2 mv^2$. How does this kinetic energy assist in a chemical reaction?

If we double the absolute temperature, the average kinetic energy of the molecules doubles. However, the rate constant $k$ for a reaction with $E_a = 50 \text{ kJ/mol}$ increases by a factor of about $10^3$. This illustrates that:

If the steric factor $P$ is much less than 1, the reaction is said to be:

Collision theory can be seen as an extension of:

The rate constant for a reaction is $1.2 \times 10^{-3} \ mol \ L^{-1} \ s^{-1}$. The order of the reaction is:

For a reaction $P + Q \rightarrow R$, the rate law is $Rate = k[P]^{1/2}[Q]^2$. The overall order is:

If the rate of reaction $A \rightarrow B$ becomes 8 times when the concentration of $A$ is doubled, the order is:

The order of the decomposition of $N_2O_5$ in the gas phase is:

If $t_{1/2}$ of a reaction is found to be independent of the initial concentration, the reaction is likely to be:

For a reaction $A \rightarrow B$, the rate law is $Rate = k[A]^{n}$. If the plot of $\log(Rate)$ vs. $\log[A]$ is a straight line, what is the slope of this line?

A reaction with a very high rate constant usually has a:

For a reaction $A \rightarrow \text{Products}$, if the concentration of $A$ is increased by a factor of $x$, and the rate increases by a factor of $y$, the order $n$ is calculated as:

For the reaction $H_2 + Br_2 \rightarrow 2HBr$, the experimental rate law is $r = k[H_2][Br_2]^{1/2}$. If the concentration of $Br_2$ is increased by 9 times while $H_2$ is kept constant, the rate will increase by:

The decomposition of $NH_3$ on a platinum surface is zero-order. If the rate constant is $2.5 \times 10^{-4} \text{ mol L}^{-1} \text{ s}^{-1}$, what are the rates of production of $N_2$ and $H_2$?

For a reaction $X \rightarrow Y$, if the molecularity is 1, the reaction is:

Molecularity is a property of the ______.

What is the maximum molecularity usually observed in chemical reactions?

Can the order of an elementary reaction be different from its molecularity?

A proposed reaction mechanism consists of two elementary steps as shown in the flowchart below. What is the molecularity of 'Step 2' in this mechanism?

The concept of molecularity is based on:

Which of the following cannot be used to define a complex reaction?

In the reaction mechanism $A + A \xrightarrow{k_1} A^* + A$ and $A^* \xrightarrow{k_2} P$, the 'molecularity' of the second step is:

The conversion of cyclopropane to propene is a unimolecular reaction. What is the molecularity of its transition state formation?

Why is the molecularity of a reaction limited to the liquid or gas phase in most CBSE Grade 12 discussions?

A substance decomposes with a half-life of 2 hours. If we start with 10M, how much is left after 6 hours?

If the half-life of a first-order reaction is 69.3 seconds, the rate constant is:

The integrated rate equation for a first-order reaction is $k = \frac{2.303}{t} \log \frac{[R]_0}{[R]}$. When $t = t_{1/2}$, then $[R]$ is:

For which order does the half-life decrease as the initial concentration increases?

For a first-order gas-phase decomposition reaction $A(g) \rightarrow B(g) + C(g)$, the system initially contains only pure $A$ at a pressure $P$. Based on the provided flowchart representing the partial pressures of the components at the half-life ($t_{1/2}$), what is the total pressure of the system at this point?

The half-life of a first-order reaction $A \rightarrow B$ is $10$ minutes. What is the rate of reaction when $[A] = 0.01 \, mol \, L^{-1}$?

If a reaction has a rate constant $k = 5 \times 10^{-4} \, mol \, L^{-1} \, min^{-1}$, the half-life for an initial concentration of $0.5 \, M$ is:

In a zero-order reaction, if the initial concentration is $a$, then the time for $2/3$ completion of the reaction is:

A first-order reaction is $50\%$ complete in 10 minutes at $27^{\circ}\text{C}$ and in 5 minutes at $37^{\circ}\text{C}$. The activation energy of the reaction is:

For a first-order reaction, if the concentration of the reactant is doubled, the half-life will: