Identify the correct statement:

Question

For first order reaction, rate constant at $27^{\circ} C$ and $t^{\circ} C$ are $1.5 \times 10^3$ and $4.5 \times 10^3$ respectively. If activation energy of the reaction is $60 \text{ kJmol}^{-1}$, then ($R = 8.3 \text{ Jmol}^{-1}K^{-1}$) $\ln 3 = 1.1$
Find temperature 't' (in $^{\circ} C$).

Answer 1

The question asks us to identify the correct statement about the molecularity of chemical reactions from the given options. Let's analyze each option:

Option 1: Molecularity of a reaction is an experimental quantity.
- Molecularity is a theoretical concept and refers to the number of molecules or atomic species that come together in a single step of a reaction mechanism. It is not determined experimentally but derived from the reaction mechanism.
Option 2: For complex reactions, molecularity has no meaning.
- Complex reactions are those with multiple steps. The molecularity concept applies only to elementary reactions, where reactions occur in a single step, not to complex or multi-step reactions. Hence, for complex reactions, molecularity indeed has no meaning. This statement is correct.
Option 3: Molecularity of a reaction can be zero or even a fraction.
- Molecularity describes the number of molecules or atoms colliding in an elementary reaction step. It must be a positive integer (1, 2, or 3) and cannot be zero or a fraction.
Option 4: Molecularity more than three is very common in chemical reactions.
- Molecularity greater than three is rare because the likelihood of four or more molecules colliding simultaneously with the correct orientation is extremely low. Such high molecularity is uncommon.

Based on the analysis above, the correct statement is: For complex reactions, molecularity has no meaning.

Answer 2

The question asks us to identify the correct statement about the molecularity of chemical reactions from the given options. Let's analyze each option:

Option 1: Molecularity of a reaction is an experimental quantity.
- Molecularity is a theoretical concept and refers to the number of molecules or atomic species that come together in a single step of a reaction mechanism. It is not determined experimentally but derived from the reaction mechanism.
Option 2: For complex reactions, molecularity has no meaning.
- Complex reactions are those with multiple steps. The molecularity concept applies only to elementary reactions, where reactions occur in a single step, not to complex or multi-step reactions. Hence, for complex reactions, molecularity indeed has no meaning. This statement is correct.
Option 3: Molecularity of a reaction can be zero or even a fraction.
- Molecularity describes the number of molecules or atoms colliding in an elementary reaction step. It must be a positive integer (1, 2, or 3) and cannot be zero or a fraction.
Option 4: Molecularity more than three is very common in chemical reactions.
- Molecularity greater than three is rare because the likelihood of four or more molecules colliding simultaneously with the correct orientation is extremely low. Such high molecularity is uncommon.

Based on the analysis above, the correct statement is: For complex reactions, molecularity has no meaning.

Identify the correct statement:

Show Hint

The Correct Option is B

Solution and Explanation

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