Ozone decomposes to oxygen according to the equation \(2 \mathrm{O}_{3}(g) \longrightarrow 3 \mathrm{O}_{2}(g) .\) Write the equation that relates the rate expressions for this reaction in terms of the disappearance of \(\mathrm{O}_{3}\) and the formation of oxygen.

Short Answer

Expert verified
The rate of disappearance of O3 relative to the rate of formation of O2 is given by the equation -1/2 (d[O3]/dt) = 1/3 (d[O2]/dt).

Step by step solution

01

Understanding the chemical equation

Examine the balanced chemical equation given: 2 O_3(g) --> 3 O_2(g). This equation shows that 2 moles of ozone (O3) decompose to form 3 moles of oxygen (O2) gas.
02

Writing the rate of disappearance of O3

The rate of disappearance of O3 can be written as the change in concentration of O3 over time, which is the rate at which O3 is being used up. It is expressed as -1/2 (d[O3]/dt).
03

Writing the rate of formation of O2

Similarly, the rate of formation of O2 is determined by the change in concentration of O2 over time. Given the stoichiometry of the reaction, it can be expressed as 1/3 (d[O2]/dt).
04

Relating the rates

Since 2 moles of O3 form 3 moles of O2, the rate of disappearance of O3 is related to the rate of appearance of O2 by a factor of their stoichiometric coefficients. The relationship is -1/2 (d[O3]/dt) = 1/3 (d[O2]/dt).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Rate of Disappearance
When we talk about the rate of disappearance in chemical reactions, we're looking at how quickly reactants are being used up. In the case of ozone (\text{O}_3), its rate of disappearance is described by the negative change in concentration over a given time period. This is because as a reactant is consumed, its concentration decreases. The 'negative' aspect comes from the convention that a decrease in concentration over time is assigned a negative value.
For our decomposition reaction of ozone to oxygen, we use the mathematical expression \[\begin{equation}-\frac{1}{2} \left(\frac{d[\text{O}_3]}{dt}\right)\end{equation}\]This signifies that for every two moles of ozone disappearing, there's a corresponding rate of disappearance, adjusted for the stoichiometry. By understanding this rate, students can evaluate how fast a reactant is being used in any given chemical process.
Rate of Formation
In contrast to the rate of disappearance, the rate of formation focuses on the products in a chemical reaction, in this instance, oxygen (\text{O}_2). We measure this rate by the positive change in concentration over time since the formation of products leads to an increase in their concentration.
Continuing with our ozone-oxygen example, the rate of formation for oxygen is mathematically represented as \[\begin{equation}\frac{1}{3} \left(\frac{d[\text{O}_2]}{dt}\right)\end{equation}\]This expression takes into account the stoichiometry which says three moles of oxygen are formed from two moles of ozone. Therefore, for every three moles of oxygen appearing, there's a corresponding rate of formation that's proportional to the amount of ozone that disappeared.
Stoichiometry
Stoichiometry is essentially the 'recipe' for a chemical reaction. It tells us the exact proportions of reactants and products involved. Like in cooking, if you alter the recipe, the final product won't be what you expected. In chemical reactions, stoichiometry is crucial for predicting the amounts of substances produced or required.
The balanced equation in our exercise, \[\begin{equation}2 \text{O}_3(g) \longrightarrow 3 \text{O}_2(g),\end{equation}\]is a stoichiometric representation that signifies for every two molecules of ozone that react, three molecules of oxygen are produced. Stoichiometry isn't just a theoretical concept; it's used in laboratories and industries worldwide to ensure that chemical processes are efficient, cost-effective, and safe.
Chemical Kinetics
Chemical kinetics deals with studying the speed or rate at which chemical reactions occur, and what affects these rates. Factors such as concentration, temperature, surface area, catalysts, and the nature of the reactants can all play significant roles.
In the context of our problem, chemical kinetics would look at how the concentration of ozone affects the rate at which it turns into oxygen, and vice versa. Even the seemingly simple decomposition of ozone is governed by the principles of kinetics, which can help predict how long it will take for a certain amount of ozone to disappear under specific conditions.Understanding kinetics is crucial for fields ranging from pharmaceuticals, where reaction rates can affect drug production, to environmental science, where the breakdown rates of pollutants can impact ecosystems.

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Most popular questions from this chapter

How will each of the following affect the rate of the reaction: \(\operatorname{CO}(g)+\mathrm{NO}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{NO}(g)\) if the rate law for the reaction is rate \(=k\left[\mathrm{NO}_{2}\right][\mathrm{CO}] ?\) (a) Increasing the pressure of \(\mathrm{NO}_{2}\) from 0.1 atm to \(0.3 \mathrm{atm}\) (b) Increasing the concentration of CO from \(0.02 M\) to \(0.06 M\)

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