Target Exam

CUET

Subject

Chemistry

Chapter

Physical: Chemical Kinetics

Question:

Match the items of List I with List II

List I List II
A. Instantaneous rate I. rate constant
B. Average rate II. rate law
C. Mathematical expression for rate of reaction in terms of concentration of reactants III. short interval of time
D. Rate of reaction for zero order reaction is equal to IV. long direction of time

Choose the correct answer from the options given below:

Options:

A-IV, B-II, C-I, D-II

A-I, B-II, C-III, D-IV

A-II, B-I, C-IV, D-III

A-III, B-IV, C-II, D-I

Correct Answer:

A-III, B-IV, C-II, D-I

Explanation:

The correct answer is option 4. A-III, B-IV, C-II, D-I.

List I List II
A. Instantaneous rate III. short interval of time
B. Average rate IV. long direction of time
C. Mathematical expression for rate of reaction in terms of concentration of reactants II. rate law
D. Rate of reaction for zero order reaction is equal to I. rate constant

Let us explore each term in detail and how they match with the definitions provided:

A. Instantaneous rate: III. short interval of time:

The instantaneous rate of a reaction refers to the rate of the reaction at a specific moment in time. It is measured over a very short time interval to capture the rate at that exact instant. It is given by the derivative of the concentration of a reactant or product with respect to time:

\(\text{Instantaneous Rate} = -\frac{d[A]}{dt}\)

where \([A]\) is the concentration of a reactant and \(t\) is time.

B. Average rate: IV. long direction of time

The average rate of a reaction is calculated over a longer period, typically from the start to the end of the reaction or over a substantial interval. It provides an overall rate over that period. It is calculated as:

\(\text{Average Rate} = \frac{\text{Change in concentration}}{\text{Change in time}}\)

For example:

\(\text{Average Rate} = \frac{[A]_t - [A]_0}{t}\)

where \([A]_t\) is the concentration at time \(t\) and \([A]_0\) is the initial concentration.

C. Mathematical expression for rate of reaction in terms of concentration of reactants: II. rate law

The rate law is an equation that expresses the rate of a chemical reaction in terms of the concentration of reactants. It shows how the reaction rate depends on the concentration of each reactant. The rate law for a reaction is given by:

\(\text{Rate} = k[A]^m[B]^n\)

where \(k\) is the rate constant, \([A]\) and \([B]\) are the concentrations of the reactants, and \(m\) and \(n\) are the reaction orders with respect to each reactant.

D. Rate of reaction for zero order reaction is equal to: I. rate constant

For a zero-order reaction, the rate of the reaction is independent of the concentration of reactants. This means that the rate remains constant as the concentration of reactants changes. The rate for a zero-order reaction is given by:

\(\text{Rate} = k\)

where \(k\) is the rate constant. Since the rate does not depend on the concentration of the reactants, the rate remains equal to the rate constant.

Summary

Instantaneous Rate: Measures the rate at a specific moment and thus is associated with a short interval of time.

Average Rate: Measures the rate over a longer duration and thus is associated with a long duration of time.

Rate Law: The mathematical expression that relates the rate of the reaction to the concentrations of reactants.

Zero-Order Reaction: The rate of reaction is constant and equal to the rate constant.

Thus, the correct answer is option 4. A-III, B-IV, C-II, D-I.