JEE CHEMISTRY MCQ: CHEMICAL KINETICS

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Analyzing +4 | -1

For the second-order reaction

{A}+{B} \rightarrow \text{Products},

the rate constant

k

, is given as

k=\frac{2.303}{(a-b) t} \log \frac{b(a-x)}{a(b-x)},

where,

a

and

b

are the initial concentrations of '

A

' and '

B

' and

x

is the change in concentration after time

t.

b \gg a,

the reaction reduces to

View answer and explanation

Correct option: A

First-order with respect to

A

Option A (First-order with respect to A) is correct because when b >> a, the concentration of B remains essentially constant, making the reaction pseudo-first-order with respect to A.

More Questions from CHEMICAL KINETICS

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The reaction

\mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB}

follows the mechanism

\begin{aligned} & {{\text{A}}_2}\mathop \rightleftharpoons \limits_{{{\text{k}}_{ - 1}}}^{{{\text{k}}_1}} {\text{A}} + {\text{A (fast) }} \\ & \mathrm{A}+\mathrm{B}_2 \xrightarrow{\mathrm{k}_2} \mathrm{AB}+\mathrm{B} \text { (slow) } \\ & \mathrm{A}+\mathrm{B} \rightarrow \mathrm{AB} \text { (fast) } \end{aligned}

The overall order of the reaction is: For the first order reaction with the rate constant

k

, which expression gives the rate half-life period?

(Initial\mathrm{ }conc.\mathrm{ } = a)

Which of the following is a zero order reaction? For a certain reaction involving a single reactant, it is found that

C_0 \sqrt{T}

is constant, where

C_0

is the initial concentration of the reactant and

T

is the half-life. What is the order of the reaction? Arrhenius equation is The energy of activation for an uncatalysed reaction is

100 \mathrm{~kJ/mol}.

Presence of a catalyst lowers the energy of activation by

75 \%

. The

\log _{10} \frac{K_2}{K_1}

of the ratio of rate constant of catalysed and uncatalysed reactions at

27^{\circ} \mathrm{C}

is?

Assume the frequency factor is same for both reactions. (Given

2.303 \times 8.314=19.147

)