Question

Which of the following is an example of second order reaction ?

• A. \(2\,\text{H}_2\text{O}_{2(l)}\rightarrow 2\text{H}_2\text{O}_{(l)}+\text{O}_{2(g)}\)
• B. \(\text{CH}_3\text{CHO}_{(g)}\rightarrow \text{CH}_{4(g)}+\text{CO}_{(g)}\)
• C. \(2\,\text{NO}_{2(g)}+\text{F}_{2(g)}\rightarrow 2\text{NO}_2\text{F}_{(g)}\)
• D. \(2\,\text{NO}_{(g)}+2\text{H}_{2(g)}\rightarrow \text{N}_{2(g)}+2\text{H}_2\text{O}_{(l)}\)

Hint:

Second order means the rate depends on the sum of powers of concentration equal to 2.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The order of a reaction comes from experiments, not from the balanced equation. Known results: hydrogen peroxide decomposition is first order, acetaldehyde decomposition is 3/2 order, and \(2\text{NO}_2 + \text{F}_2 \rightarrow 2\text{NO}_2\text{F}\) follows \(r = k[\text{NO}_2][\text{F}_2]\).

Step 2: Go through the options:
(A) \(r = k[\text{H}_2\text{O}_2]\), first order.
(B) \(r = k[\text{CH}_3\text{CHO}]^{3/2}\), order 1.5.
(C) \(r = k[\text{NO}_2][\text{F}_2]\), order 1 + 1 = 2, second order.
(D) \(r = k[\text{NO}]^2[\text{H}_2]\), third order.

Final Answer:
Reaction (C) is of second order. \[ \boxed{\text{(C)}} \]