Question

The half-life of the first order reaction \[ \text{CH}_3\text{CHO} (g) \rightarrow \text{CH}_4 (g) + \text{CO} (g) \] If initial pressure of \( \text{CH}_3\text{CHO} \) is 80 mm Hg and the total pressure at the end of 20 minutes is 120 mm Hg

• A. 80 minutes
• B. 120 minutes
• C. 40 minutes
• D. 60 minutes

Hint:

For first-order reactions, the pressure change is directly related to the change in concentration of reactants.

Answer 1

The Correct Option is C

Step 1: Understand the relationship between the pressure and half-life.
For a first-order reaction, the total pressure increases as the reaction progresses, and the pressure is related to the concentration of the reactant.
Step 2: Conclusion.
The half-life is 40 minutes, based on the given data.
Final Answer: \[ \boxed{40 \, \text{minutes}} \]