Elementary and Complex Reactions

Q. One litre of 2M acetic acid is mixed with one litre of 3M ethyl alcohol to form ester $C{H}_{3}COOH+C_2{H}_{5}OH\iff C{H}_{3}COO{C}_2{H}_5+H_{2}O$. The decrease in the initial rate if each solution is diluted by an equal volume of water would be

1. 0.5 times
2. 2 times
3. 4 times
4. 0.25 times

Q. The decomposition of ozone proceeds as $O_3\iff O_2+O\left(fast\right)O+O_3\to 2O_2\left(slow\right)$
The rate expression should be

1. $r=k\left[O_3\right][O_2{]}^{-1}$
2. $r=k\left[O_3\right]\left[O_2\right]$
3. $r=k\left[O_3{]}^2\right[O_2{]}^{-1}$
4. $r=k[O_3{]}^2$

Q. A hypothetical reaction :
$A_2+B_2\to 2AB$ follows the following mechanism :
$A_2\iff A+A\left(fast\right)$....K
$A+B_2\to AB+B\left(slow\right)$
$A+B\to AB\left(fast\right)$
The order of the overall reaction is

1. 2
2. 1
3. 0
4. $\frac{3}{2}$

Q. For the reaction $A+B\to C+D$, the variation of the concentration of the products is given by the curve:

1. x
2. y
3. z
4. w

Q.

Samwell is almost done!
Elementary reactions are classified based on?

1. Order
2. Rate constant
3. Molecularity
4. Phase of reactants

Q. Samwell has to answer 2 final questions to become the junior Maester. Let's help him.
Elementary reactions are so called because?

1. They are the basic reactions of nature
2. They have just 2 reactants.
3. They take place in a single step.
4. They give rise to exactly one product.

Q. In the following reaction :
$2NO+O_2\stackrel{k^{\prime }}{\to }2N{O}_2$
What is the predicted rate law, if the mechanism is given as :
$NO+O_2\stackrel{K_{eq}}{\rightleftharpoons }N{O}_3$ (Fast)
$N{O}_3+NO\stackrel{k_1}{\to }N{O}_2+N{O}_2$ (Slow)

1. $r=k_1{K}_{eq}\left[NO\right]\left[O_2\right]\left[N{O}_3\right]$
2. $r=k_1{K}_{eq}\left[NO\right]\left[O_2\right]$
3. $r=k_1{K}_{eq}\left[NO{]}^2\right[O_2]$
4. $r=k_1{K}_{eq}[NO{]}^2$

Q. For the reaction $2\mathrm{NO}+{\mathrm{Br}}_2\to 2\mathrm{NOBr}$the following mechanism has been given:
$\mathrm{NO}+{\mathrm{Br}}_2\rightleftharpoons {\mathrm{NOBr}}_2$
${\mathrm{NOBr}}_2+\mathrm{NO}\to 2\mathrm{NOBr}\left(\mathrm{slow}\right)$
Hence, the rate law is :

1. $k\left[NO{]}^2\right[B{r}_2]$
2. $k\left[NO\right]\left[B{r}_2\right]$
3. $k\left[NO\right][B{r}_2{]}^2$
4. $k\left[NOB{r}_2\right]\left[NO\right]$

Q. The reaction $A_2+B_2\to 2\mathrm{AB}$, is bound to obey the following mechanism
$A_2\stackrel{k_1}{\underset{k_{-1}}{\rightleftarrows }}A+A\left(\mathrm{fast}\right)$
$A+B_2\stackrel{k_2}{\to }\mathrm{AB}+B\left(\mathrm{slow}\right)$
$A+B\to \mathrm{AB}\left(\mathrm{fast}\right)$
The order of overall reaction is

1. 3
2. 2
3. 1.5
4. 2.5

Q. Lindemann proposed the following detailed mechanism for gas phase isomerization, the reaction is

In the above scheme, $A^{\ast }$ is a molecule that has enough vibrational energy to decompose or isomerise. The Lindemann mechanism is followed by most of gas phase decomposition or isomerization reaction.
For the overall unimolecular isomerization of cyclopropane to propylene at , the values of versus concentration is as follows.
$\underset{k_{unit}}{\left|M\right|}\underset{\frac{1}{137.5}}{\left|1M\right|}\underset{\frac{1}{131.25}{\text{in s}}^{-1}}{\left|2M\right|}$

As per Lindemann mechanism $k_{unit}$ is

1. $k_{unit}=\frac{k_1{k}_2}{k_{-1}}$
2. $\frac{1}{k_{unit}}=\frac{k_{-1}}{k_1{k}_2}+\frac{k_1}{\left[M\right]}$
3. $\frac{1}{k_{unit}}=\frac{k_{-1}}{k_1{k}_2}+\frac{\left[M\right]}{k_1}$
4. $\frac{1}{k_{unit}}=\frac{k_{-1}}{k_1{k}_2}+\frac{1}{k_1}\times \frac{1}{\left[M\right]}$