Question

2N₂O(g) → 2N,(g) + 0(g)

The rate law for the reaction represented above is experimentally determined to be rate kN₂O). Which of the following best explains why increasing the initial concentration of N₂O(g) ata constant temperature increases the reaction rate?
A. Molecular collisions become more frequent
b. There is a higher probability of effective molecular collisions.
c. The tate constant for the reaction increases.
d. The reaction mechanism changes to one that has a lower activation energy

Answer 1

Understanding chemical reactions, like the formation of NO₂ from NO and O₂, relies on analyzing elementary steps rather than the overall termolecular appearance. Le Châtelier's principle explains how equilibrium shifts in response to changes in concentration, pressure, volume, or temperature. Specifically, adding more O₂ will adjust the equilibrium to produce more NO, and temperature changes can alter the equilibrium constant, Keq.

Step-by-step explanation:

The chemical reaction involving nitrogen and oxygen molecules can be understood through a two-step mechanism. In the first elementary step, two NO molecules react to form N₂O₂, and in the second step, N₂O₂ reacts with O₂ to form two NO₂ molecules. Despite the overall reaction appearing to involve three molecules (— a termolecular reaction), the individual steps, which are bimolecular, define the molecular mechanism. For example:

• Step 1: 2NO(g) → N₂O₂(g)
• Step 2: N₂O₂(g) + O₂(g) → 2NO₂(g)

Activation energy and temperature also play significant roles in these reactions. For instance, an increase in temperature can shift the equilibrium in favor of an endothermic reaction, as seen in the breakdown of N₂O₄ to NO₂.

When a system at equilibrium is subjected to a change in concentration, pressure, volume, or temperature, the system adjusts to counteract the effect of the applied stress, according to Le Châtelier's principle. Adding more O₂ will shift the equilibrium to reduce the change, increasing the production of NO in response to the additional O₂. Meanwhile, changing the temperature can shift the equilibrium and alter the value of Keq, affecting the concentrations of reactants and products in favor of one side of the reaction.