Chemical Kinetics - Result Question 13
####14. Consider the given plots for a reaction obeying Arrhenius equation $\left(0^{\circ} C<T<300^{\circ} C\right)$ : ( $k$ and $E _a$ are rate constant and activation energy, respectively)
(2019 Main, 10 Jan I)
Choose the correct option.
(a) Both I and II are wrong
(b) Both I and II are correct
(c) I is wrong but II is right
(d) I is right but II is wrong
15 For the reaction, $2 A+B \longrightarrow$ products
When concentration of both $(A$ and $B$ ) becomes double, then rate of reaction increases from $0.3 mol L^{-1} s^{-1}$ to $2.4 mol L^{-1} s^{-1}$.
When concentration of only $A$ is doubled, the rate of reaction increases from $0.3 mol L^{-1} s^{-1}$ to $0.6 mol L^{-1} s^{-1}$.
Which of the following is true?
(2019 Main, 9 Jan II)
(a) The whole reaction is of 4 th order
(b) The order of reaction w.r.t. $B$ is one
(c) The order of reaction w.r.t. $B$ is 2
(d) The order of reaction w.r.t. $A$ is 2
16 The following results were obtained during kinetic studies of the reaction;
(2019 Main, 9 Jan I)
| $2 A+B \longrightarrow$ Products | |||
|---|---|---|---|
| Experiment | $[\boldsymbol{A}]$ (in $\left.mol L^{-1}\right)$ |
$[\boldsymbol{B}]$ (in $\left.mol L^{-1}\right)$ |
Initial rate of reaction (in $\left.mol L^{-1} min^{-1}\right)$ |
| I. | 0.10 | 0.20 | $6.93 \times 10^{-3}$ |
| II. | 0.10 | 0.25 | $6.93 \times 10^{-3}$ |
| III. | 0.20 | 0.30 | $1.386 \times 10^{-2}$ |
The time (in minutes) required to consume half of $A$ is
(a) 5
(b) 10
(c) 100
(d) 1
Show Answer
Answer:
Correct Answer: 14. (d)
Solution:
- The Arrhenius equation is,
$$ k=A \cdot e^{-E _a / R T} $$
where, $k=$ rate constant,
$$ A=\text { Arrhenius constant }, E _a=\text { activation energy, } $$
and $T=$ temperature in $K$
From the equation, it is clear that $k$ decreases exponentially with $E _a$. So, the plot-I is correct.
In the plot-II, $k$ is plotted with temperature (in ${ }^{\circ} C$ but not in $K$ ). So, at $0^{\circ} C, k \neq 0$ and $k$ will increase exponentially with temperature upto $300^{\circ} C$. Therefore, the plot-II is also correct.
