Rate Constant

Q. The rate of a first order reaction is $1.8\times {10}^{-3}mol{L}^{-1}mi{n}^{-1},$ when the initial concentration is 0.3 mol $L^{-1}$ . The rate constant in the units of second is

1. ${10}^{-4}{s}^{-1}$
2. $6\times {10}^{-2}{s}^{-1}$
3. ${10}^{-2}{s}^{-1}$
4. $6\times {10}^2{s}^{-1}$

Q. For the reaction: $2A+B\to A_{2}B$ the $rate=k\left[A\right][B{]}^2$ with $k=2.0\times {10}^{-6}{\text{mol}}^{-2}{\text{L}}^2{\text{S}}^{-1}$. If the initial concentration of $A$ and $B$ are $0.1\text{mol}{\text{L}}^{-1}$ and $0.2{\text{mol L}}^{-1}$ respectively then which of the following is /are correct:

1. When $A$ is reduced to $0.06mol{L}^{-1}$ then rate becomes $3.89\times {10}^{-9}mol{L}^{-1}Se{c}^{-1}$
2. When $A$ is reduced to $0.06mol{L}^{-1}$ then $B$ will be $0.16mol{L}^{-1}$
3. All are correct
4. Initial rate of reaction is $8\times {10}^{-9}{\text{mol L}}^{-1}{\text{S}}^{-1}$

Q. For the first order decomposition reaction of $N_2{O}_5$, it is observed that
$\left(i\right)N_2{O}_5\left(g\right)\to 2N{O}_2\left(g\right)+\frac{1}{2}{O}_2\left(g\right);\frac{-d\left[N_2{O}_5\right]}{dt}=k\left[N_2{O}_5\right]\left(ii\right)2N_2{O}_5\left(g\right)\to 4N{O}_2\left(g\right)+O_2\left(g\right);\frac{-d\left[N_2{O}_5\right]}{dt}=k^{\prime }\left[N_2{O}_5\right]$
Which of the following is true?

1. $k=k^{\prime }$
2. $k=\frac{k^{\prime }}{2}$
3. $k=2k^{\prime }$
4. $k=k^{\prime \frac{1}{2}}$

Q. A gaseous reaction A(g) $\leftrightarrow$ 2B(g) + C(g) is found to be of first order. If the reaction is started with p_A = 90 mm Hg, the total pressure after 10 min is found to be 180 mm Hg. The rate constant of the reaction is

1. $4.60\times {10}^{-3}{s}^{-1}$
2. $4.90\times {10}^{-3}{s}^{-1}$
3. $1.15\times {10}^{-3}{s}^{-1}$
4. $6.9\times {10}^{-2}{s}^{-1}$

Q. In Samwell's classes, the Maesters made the following statements. He had to figure out how many were right. Can you help him?

Maester 1 said: Rate constant is characteristic of a reaction
Maester 2 said: Rate constant is dependent on temperature
Maester 3 said: Rate constant is not dependent on the catalyst

1. One was right
2. Two were right
3. Three were right
4. None were right

Q. It is possible to have a reaction where the rate of the reaction increases but the rate constant decreases.

1. False
2. True

Q.

Mr. Samwell Tarly has to learn Chemistry to become a Maester. He is stuck with Kinetics. Will you help him?

(Maester is just Master in their language)

Choose the appropriate definition of rate constant.

1. The concentration when rate of reaction is equal to $1mol{L}^{-1}se{c}^{-1}$
2. The constant which is added to the rate equation to make everything equal to one.
3. The rate of the reaction when concentration of reactants is equal to one.
4. The constant which relates rate of reaction to the temperature.

Q. For the non-stoichiometric reaction 2A + B ⟶ C + D. The following kinetic data were obtained in three separate experiments, all at 298 K.

Initial concentration (A)	Initial concentration (B)	Initial rate of formation of C $\left(mol{L}^1{S}^{-1}\right)$
0.1M	0.1M	$1.2\times {10}^{-3}$
0.1M	0.2M	$1.2\times {10}^{-3}$
0.2M	0.1M	$2.4\times {10}^{-3}$

The rate law for the formation of C is :
(IIT-JEE-2014)

1. $\frac{dc}{dt}=k\left[A\right]$

2. $\frac{dc}{dt}=k\left[A\right]\left[B\right]$
3. $\frac{dc}{dt}=k\left[A{]}^2\right[B]$

4. $\frac{dc}{dt}=k\left[A\right][B{]}^2$

Q. The specific rate constant of a first order reaction depends on the:

1. concentration of the reactant
2. concentration of the product
3. time
4. temperature

Q.

A reaction : $A_2+B\to$ Products, involves the following mechanism :
$A_2\rightleftharpoons 2A\left(fast\right)$ (A being the intermediate)
$A+B\underset{k_2}{\to }\left(slow\right)$.The rate law consistent to this mechanism is :

1. $rate=k\left[A_2\right]\left[B\right]$

2. $rate=k\left[A_2{]}^2\right[B]$

3. $rate=k\left[A_2{]}^{\frac{1}{2}}\right[B]$

4. $rate=k\left[A_2\right][B{]}^2$