Question

2 nobr(g) → 2 no(g) + br₂(g)
the equation above represents an elementary step in a chemical reaction. which of the following is the correct expression for the rate law of the elementary step?
a rate = knobr^(½)
b rate = knobr
c rate = knobr²
d rate = kno²br₂

Explanation:

Step1: Recall rate law for elementary steps

For an elementary reaction (a single-step reaction), the rate law is determined by the stoichiometric coefficients of the reactants. The general form for a reaction \( aA + bB
ightarrow \text{products} \) is \( \text{Rate} = k[A]^a[B]^b \).

Step2: Analyze the given elementary reaction

The reaction is \( 2\text{NOBr}(g)
ightarrow 2\text{NO}(g) + \text{Br}_2(g) \). Here, the reactant is \( \text{NOBr} \) with a stoichiometric coefficient of 2.

Step3: Determine the rate law

Using the rule for elementary reactions, the rate law should be \( \text{Rate} = k[\text{NOBr}]^2 \), since the coefficient of \( \text{NOBr} \) is 2.

Answer:

C. Rate = \( k[\text{NOBr}]^2 \)