Question

The order for the given reaction is: \[ \text{A} + 2\text{B} \rightarrow \text{Products} \] \[ \text{Rate} = k[\text{A}]^{1/2}[\text{B}]^{1} \]

• A. 1.5
• B. 1
• C. 0.5
• D. 2

Hint:

Order of reaction = sum of powers in rate law, not from balanced equation. Fractional orders are possible in complex reactions.

Answer 1

The Correct Option is A

Concept: The order of a reaction is the sum of the powers of concentration terms in the rate law. \[ \text{Order} = \text{Sum of exponents in rate equation} \] It is determined experimentally and may not match stoichiometric coefficients.
Step 1: Write the given rate law. \[ \text{Rate} = k[\text{A}]^{1/2}[\text{B}]^{1} \]
Step 2: Add the powers of concentrations. Order with respect to A = $1/2$ Order with respect to B = $1$
Step 3: Calculate overall order. \[ \text{Overall order} = \frac{1}{2} + 1 = \frac{3}{2} = 1.5 \]