Question

Identify the order of following reaction: $2\text{NO}_{2}(g)\rightarrow2\text{NO}(g)+\text{O}_{2}(g)$.

• A. 1
• B. 1.5
• C. 2
• D. 3

Hint:

While order is an experimental fact, textbook examples are fixed.
$2\text{N}_2\text{O}_5 \rightarrow 4\text{NO}_2 + \text{O}_2$ is First Order.
$2\text{NO}_2 \rightarrow 2\text{NO} + \text{O}_2$ is Second Order.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We are given the balanced chemical equation for the thermal decomposition of nitrogen dioxide gas. We need to state its experimentally determined order of reaction.

Step 2: Detailed Explanation:
The order of a chemical reaction is a strictly experimental quantity; it cannot be reliably predicted just by looking at the stoichiometric coefficients of a balanced complex chemical equation.
However, the thermal decomposition of nitrogen dioxide is a highly famous, classical example of a second-order reaction taught in standard chemical kinetics curriculum.
The experimentally determined rate law for this specific decomposition process is:
$\text{Rate} = k [\text{NO}_2]^2$
Because the concentration term $[\text{NO}_2]$ is raised to the power of 2, the overall order of the reaction is exactly 2.
(Note: In this specific rare case, the order perfectly matches the stoichiometric coefficient of the reactant, meaning it could potentially proceed as a simple elementary bimolecular collision step).

Step 3: Final Answer:
The order of the reaction is 2, matching option (c).