Question

Write the rate expression for each of the following elementary steps: (a) \(\mathrm{Cl}_{2} \longleftrightarrow 2 \mathrm{Cl}\) (b) \(\mathrm{N}_{2} \mathrm{O}_{2}+\mathrm{O}_{2} \longrightarrow 2 \mathrm{NO}_{2}\) (c) \(\mathrm{I}^{-}+\mathrm{HClO} \longrightarrow \mathrm{HIO}+\mathrm{Cl}^{-}\)

Short answer

Question: Write the rate expressions for the following elementary steps: a) Cl₂ ↔ 2 Cl b) N₂O₂ + O₂ → 2 NO₂ c) I⁻ + HClO → HIO + Cl⁻ Answer: a) Forward reaction: Rate = \(k_1[\mathrm{Cl}_{2}]\); Reverse reaction: Rate = \(k_{-1}[\mathrm{Cl}]^2\) b) Rate = \(k_2[\mathrm{N}_{2} \mathrm{O}_{2}][\mathrm{O}_{2}]\) c) Rate = \(k_3[\mathrm{I}^{-}][\mathrm{HClO}]\)

Step-by-step solution

Elementary step (a):

Given the elementary step: \(\mathrm{Cl}_{2} \longleftrightarrow 2 \mathrm{Cl}\). This is a reversible reaction, so we need to write rate expressions for both the forward and reverse reactions. Forward reaction: Rate = \(k_1[\mathrm{Cl}_{2}]\) Reverse reaction: Rate = \(k_{-1}[\mathrm{Cl}]^2\)

Elementary step (b):

Given the elementary step: \(\mathrm{N}_{2} \mathrm{O}_{2}+\mathrm{O}_{2} \longrightarrow 2 \mathrm{NO}_{2}\). This is a one-way reaction, so we only need to write a rate expression for the forward reaction. Rate = \(k_2[\mathrm{N}_{2} \mathrm{O}_{2}][\mathrm{O}_{2}]\)

Elementary step (c):

Given the elementary step: \(\mathrm{I}^{-}+\mathrm{HClO} \longrightarrow \mathrm{HIO}+\mathrm{Cl}^{-}\). This is also a one-way reaction, so we only need to write a rate expression for the forward reaction. Rate = \(k_3[\mathrm{I}^{-}][\mathrm{HClO}]\) Now we have written the rate expressions for all given elementary steps.