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

The order of a reaction is determined by the sum of the powers of the concentration terms in the rate law expression. The given reaction is:

\[\text{A} + 2\text{B} \rightarrow \text{Products}\]

and the rate law is given as:

\[\text{Rate} = k[\text{A}]^{1/2}[\text{B}]^{1}\]

To find the order of the reaction, we need to add the exponents of the concentration terms in the rate expression.

• The exponent of \([\text{A}]\) is \(\frac{1}{2}\).
• The exponent of \([\text{B}]\) is \(1\).

Therefore, the overall order of the reaction is the sum of these exponents:

\[\text{Order} = \frac{1}{2} + 1 = \frac{3}{2} = 1.5\]

Thus, the order of the reaction is 1.5.

This matches the correct answer option: \(1.5\).

Explanation: In chemical kinetics, the order of a reaction characterizes the relationship between the concentration of reactants and the rate of reaction. Here, the fractional order for \([\text{A}]\) indicates a complex mechanism, possibly involving a chain of steps. Always add the powers to get the overall order when multiple reactants are involved.