Two parallel mechanistic pathways have been suggested for the overall conversion of…

CHEMISTRY · Multi-part · AP · Chemistry · Kinetics · Kinetics

Problem

Two parallel mechanistic pathways have been suggested for the overall conversion of nitrogen(II) oxide and oxygen to nitrogen(IV) oxide under atmospheric conditions. Pathway A: Step 1 NO  +  O3  ⟶  NO2  +  O2\mathrm{NO \; + \; O_3 \; \longrightarrow \; NO_2 \; + \; O_2} Step 2 NO2  +  O  ⟶  NO  +  O2\mathrm{NO_2 \; + \; O \; \longrightarrow \; NO \; + \; O_2} Pathway B: Step 1 NO  +  O2  ⟶  NO3\mathrm{NO \; + \; O_2 \; \longrightarrow \; NO_3} Step 2 NO3  +  NO  ⟶  2 NO2\mathrm{NO_3 \; + \; NO \; \longrightarrow \; 2\,NO_2} Ozone (O3\mathrm{O_3}) is present at trace levels in the air. Atomic oxygen (O\mathrm{O}) is generated photochemically. The species NO\mathrm{NO} therefore participates in both pathways. (a) Combine the elementary steps of Pathway A to obtain its overall equation. Repeat for Pathway B. (b) In a single table, list every chemical species that appears in either pathway and, for each pathway separately, classify the species as reactant, product, intermediate, or catalyst. If a species does not participate in a given pathway, write “not present.” (c) For the species NO\mathrm{NO}, explain how its role differs between the two pathways and rationalize why its dual function could complicate kinetic analysis of the atmospheric process.

Related theory

Browse the problem library