Question

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

• A. 1.5
• B. 1
• C. 0.5
• D. 2

Hint:

Order = Sum of powers in the rate law. Do not use the coefficients from the balanced reaction equation.

Answer 1

The Correct Option is A

Step 1: What determines reaction order?
The overall order of a reaction is found entirely from the experimentally determined rate law, not from the stoichiometric coefficients in the balanced equation.
Step 2: Read the rate law.
The given rate law is $\text{Rate} = k[A]^{1/2}[B]^1$. The exponent for $[A]$ is $\frac{1}{2}$ and for $[B]$ is $1$.
Step 3: Sum the exponents.
Overall order $= \frac{1}{2} + 1 = \frac{3}{2} = 1.5$. The stoichiometric coefficient of $B$ (which is 2) is irrelevant to the order.
Step 4: Identify the correct option.
An overall order of 1.5 is fractional, indicating a complex mechanism. This matches option (A).
\[ \boxed{(A)} \]