Question

For the reaction A + B → Products, the rate law is \( r = k[\text{A}]^{1/2}[\text{B}]^2 \). What is the order of the reaction?

• A. 1.5
• B. 2.5
• C. 2
• D. 3

Hint:

Add the exponents of each reactant in the rate law to get the total order of the reaction—even fractional powers count!

Answer 1

The Correct Option is B

To determine the order of a reaction, we sum the powers of the concentration terms in the rate law.
Given rate law: \[ r = k[\text{A}]^{1/2}[\text{B}]^2 \] - Order with respect to A = \( \frac{1}{2} \)
- Order with respect to B = \( 2 \)
Therefore, total order of the reaction = \[ \frac{1}{2} + 2 = \frac{5}{2} = 2.5 \] Hence, the order of the reaction is 2.5.