Question

For a reaction A → B, the concentration of A decreases from 0.8 M to 0.2 M in 10 minutes. If the rate constant is 0.1 min⁻¹, what is the order of the reaction?

• A. 0
• B. 1
• C. 2
• D. 3

Hint:

For first-order reactions, use the equation \( \ln \frac{[A_0]}{[A]} = kt \) to calculate the reaction order.

Answer 1

The Correct Option is B

The rate law for a reaction is given by: \[ \text{Rate} = k[A]^n, \] where \( n \) is the order of the reaction and \( k \) is the rate constant. The integrated rate law for a first-order reaction is: \[ \ln \frac{[A_0]}{[A]} = kt, \] where \( [A_0] = 0.8 \, \text{M} \), \( [A] = 0.2 \, \text{M} \), and \( t = 10 \, \text{minutes} \). Substitute the values: \[ \ln \frac{0.8}{0.2} = 0.1 \times 10. \] Simplifying: \[ \ln 4 = 1. \] Thus, the reaction is first-order, so the correct answer is: \[ \boxed{1}. \]