Question

\(3 \mathrm{~A} \longrightarrow \mathrm{B}+\mathrm{C}\) It would be a zero order reaction when (a) the rate of reaction is proportional to square of concentration of \(\mathrm{A}\) (b) the rate of reaction remains same at any concentration of \(\mathrm{A}\) (c) the rate remains unchanged at any concentration of \(\mathrm{B}\) and \(\mathrm{C}\) (d) the rate of reaction doubles if concentration of is increased to double

Short answer

(b) the rate of reaction remains same at any concentration of \( \mathrm{A} \).

Step-by-step solution

Understand Zero Order Reaction Definition

A zero order reaction is defined as one in which the rate of reaction is independent of the concentration of the reactants. This means that the rate remains constant and is not affected by changes in the concentrations of the reactants.

Analyze Each Option

Review each option to see which one describes a scenario where the rate of reaction does not depend on the concentration of reactants.- (a) The rate of reaction is proportional to the square of concentration of \( \mathrm{A} \). This implies that the rate depends on the concentration of \( \mathrm{A} \), which is not zero order.- (b) The rate of reaction remains same at any concentration of \( \mathrm{A} \). This implies the rate is constant, regardless of \( \mathrm{A} \)'s concentration, fitting the definition of zero order.- (c) The rate remains unchanged at any concentration of \( \mathrm{B} \) and \( \mathrm{C} \). The rate independent of \( \mathrm{B} \) and \( \mathrm{C} \) aligns with zero order if it's independent of all reactants, but we focus on \( \mathrm{A} \), since that's the specified reactant.- (d) The rate of reaction doubles if concentration of \( \mathrm{A} \) is increased. This shows dependency on \( \mathrm{A} \), not fitting zero order.

Conclusion

Based on the definition of a zero order reaction, option (b) is consistent with the reaction being zero order as it specifies that the rate is constant at any concentration of \( \mathrm{A} \). The other options imply some dependency on reactant concentration which is not characteristic of a zero order reaction.

Key concepts

Rate of Reaction

In the context of chemical reactions, the rate of reaction refers to how swiftly reactants are transformed into products within a given time frame. It is an essential aspect of chemistry to understand, as it helps predict how long a reaction will take to complete. Generally, for most reactions, the rate depends significantly on the concentration of reactants — higher concentrations usually increase the reaction rate. However, this is not always the case.

For a zero order reaction, the rate is rather unique; it is characterized by being constant regardless of the reactants' concentration. This means that even if you add more of a reactant, the speed at which products are formed will not increase. In simpler terms, zero order reactions proceed at a fixed pace no matter how much starting material you have.

In equations, the rate of a zero order reaction can be described using the formula:
\[ \text{Rate} = k \]
where \( k \) is the rate constant. This equation illustrates that for a zero order reaction, the rate is directly equal to the rate constant and remains consistent unless externally changed by factors like temperature or catalysts.

Concentration Dependency

Concentration dependency in reaction kinetics often explores how altering the concentration of reactants affects the speed of a chemical reaction. In many reactions, particularly of the first or second order, there is a definitive relationship: increase the concentration of a reactant, and the rate typically increases.

However, in a zero order reaction, as fascinatingly unique as it is, the rate is completely independent of the concentration of reactants. This means whether you have a little or a lot of reactant, the amount does not change how quickly the reaction happens. This property is critical for distinguishing zero order reactions from other types.

Consider zero order reactions like a conveyor belt machine set to a particular speed; adding more items does not make them move through faster. Instead, the conveyor moves at its own fixed speed regardless of how many items are at the start, mimicking how zero order reactions do not depend on concentration changes. This quirky characteristic makes them a vital study focus within chemical kinetics.

Chemical Kinetics

Chemical kinetics is a branch of chemistry dedicated to studying the speed or rate of chemical processes and the variables that influence these rates. Understanding kinetics is crucial for predicting reaction behavior and is applied in countless practical fields, from developing pharmaceuticals to improving industrial processes.

At the heart of chemical kinetics lies the rate equation, which relates the rate of reaction to the concentration of reactants. This equation varies for different reaction orders, establishing a framework for understanding how changes in reactant amounts affect the rate. Specifically, for zero order reactions, the equation simplifies significantly, reflecting their unique concentration independence.

Kinetics also delves into the mechanism behind reactions — detailing the steps and stages a reaction undergoes from start to finish. This mechanism offers insights into how reactions can be manipulated or controlled. By understanding the kinetics and mechanisms, scientists can predict and optimize reactions, leading to more efficient industrial processes.

Moreover, chemical kinetics enriches knowledge about the effects of additional factors, such as temperature, pressure, and catalysts, on reaction rates. Studying these interactions helps chemists create favorable conditions to drive reactions in desired ways, ensuring optimal performance across various applications.