Problem 13
Question
The oxidation of \(\mathrm{SO}_{2}\) by \(\mathrm{O}_{2}\) to \(\mathrm{SO}_{3}\) is an exothermic reaction. The yield of \(\mathrm{SO}_{3}\) will \(\mathrm{w}\) maximum if (a) temperature is increased and pressure is kept constant (b) temperature is reduced and pressure is increased (c) both temperature and pressure are increased (d) both temperature and pressure are reduced
Step-by-Step Solution
Verified Answer
(b) temperature is reduced and pressure is increased
1Step 1: Understand the Reaction
The oxidation of sulfur dioxide to sulfur trioxide is given by the reaction: \[ 2\mathrm{SO}_{2} + \mathrm{O}_{2} \rightarrow 2\mathrm{SO}_{3} \]. This reaction is exothermic, meaning it releases heat.
2Step 2: Effect of Temperature
According to Le Chatelier's Principle, for an exothermic reaction, increasing the temperature will shift the equilibrium to the left, favoring the reactants, thus reducing the yield of \(\mathrm{SO}_{3}\). Conversely, reducing the temperature will shift the equilibrium to the right, favoring the production of \(\mathrm{SO}_{3}\).
3Step 3: Effect of Pressure
The reaction involves a decrease in the number of moles of gas (from 3 moles of gas on the reactant side to 2 moles on the product side). Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas, which in this case is the product side, thereby increasing the yield of \(\mathrm{SO}_{3}\).
4Step 4: Combining Temperature and Pressure Effects
To maximize the yield of \(\mathrm{SO}_{3}\), we should reduce the temperature (as it is an exothermic reaction) and increase the pressure (since fewer moles of gas are produced). Thus, option (b) matches these conditions.
Key Concepts
Le Chatelier's PrincipleEffect of Temperature on Reaction YieldEffect of Pressure on Reaction YieldOxidation Reactions
Le Chatelier's Principle
Le Chatelier's Principle is a fundamental concept in chemistry that helps predict how a chemical reaction will respond to changes in conditions like temperature, pressure, and concentration. When a system at equilibrium experiences a change in these conditions, the equilibrium shifts to counteract the imposed change and restore balance.
In the context of an exothermic reaction, like the oxidation of \(\mathrm{SO}_{2}\), if you increase the temperature, the reaction shifts towards the reactants. Conversely, lowering the temperature will encourage the formation of more products. This principle helps chemists control reactions to favor the production of desired compounds, like maximizing the yield of \(\mathrm{SO}_{3}\) in this reaction. It empowers decision-making for optimizing industrial processes.
In the context of an exothermic reaction, like the oxidation of \(\mathrm{SO}_{2}\), if you increase the temperature, the reaction shifts towards the reactants. Conversely, lowering the temperature will encourage the formation of more products. This principle helps chemists control reactions to favor the production of desired compounds, like maximizing the yield of \(\mathrm{SO}_{3}\) in this reaction. It empowers decision-making for optimizing industrial processes.
Effect of Temperature on Reaction Yield
Temperature is a crucial factor in determining the direction and yield of a chemical reaction. For an exothermic reaction, an increase in temperature adds heat, which the system perceives as a product.
According to Le Chatelier's Principle, the system will adjust to reduce the effect of this change by shifting the equilibrium towards the reactants and decreasing the yield of the products – in this case, \(\mathrm{SO}_{3}\).
Lowering the temperature removes heat from the system. The reaction will then move towards the product side to generate heat, increasing the yield of \(\mathrm{SO}_{3}\).
According to Le Chatelier's Principle, the system will adjust to reduce the effect of this change by shifting the equilibrium towards the reactants and decreasing the yield of the products – in this case, \(\mathrm{SO}_{3}\).
Lowering the temperature removes heat from the system. The reaction will then move towards the product side to generate heat, increasing the yield of \(\mathrm{SO}_{3}\).
- Increased Temperature: Yield of \(\mathrm{SO}_{3}\) decreases
- Decreased Temperature: Yield of \(\mathrm{SO}_{3}\) increases
Effect of Pressure on Reaction Yield
Pressure plays a significant role in chemical reactions, particularly those involving gases. The principle is straightforward: increasing pressure in a reaction involving gases will shift the equilibrium towards the side with fewer moles of gas particles.
In the oxidation of sulfur dioxide to sulfur trioxide, the reaction consumes three moles of reactants (2 \(\mathrm{SO}_{2}\) + 1 \(\mathrm{O}_{2}\)) and produces two moles of sulfur trioxide (\(2\mathrm{SO}_{3}\))).
This means increasing pressure favors the forward reaction, enhancing the formation of \(\mathrm{SO}_{3}\). Decreasing pressure would have the opposite effect, shifting equilibrium towards the reactants.
In the oxidation of sulfur dioxide to sulfur trioxide, the reaction consumes three moles of reactants (2 \(\mathrm{SO}_{2}\) + 1 \(\mathrm{O}_{2}\)) and produces two moles of sulfur trioxide (\(2\mathrm{SO}_{3}\))).
This means increasing pressure favors the forward reaction, enhancing the formation of \(\mathrm{SO}_{3}\). Decreasing pressure would have the opposite effect, shifting equilibrium towards the reactants.
- Increased Pressure: More \(\mathrm{SO}_{3}\) produced
- Decreased Pressure: Less \(\mathrm{SO}_{3}\) produced
Oxidation Reactions
Oxidation reactions involve the transfer of electrons between substances, usually resulting in an increase in the oxygen content of a molecule. The specific reaction of oxidizing \(\mathrm{SO}_{2}\) to \(\mathrm{SO}_{3}\) is classic oxidation where sulfur's oxidation state increases.
This is an exothermic process, meaning it releases energy, often in the form of heat, as new bonds form. These reactions are critical in many industrial processes, including the production of sulfuric acid, one of the most widely produced chemicals worldwide.
Understanding oxidation and its impact on the thermal and dynamic aspects of a reaction can help optimize conditions for maximum productivity in chemical processes. This knowledge is vital for predicting how oxidation states change in reactions and the energy implications involved.
This is an exothermic process, meaning it releases energy, often in the form of heat, as new bonds form. These reactions are critical in many industrial processes, including the production of sulfuric acid, one of the most widely produced chemicals worldwide.
Understanding oxidation and its impact on the thermal and dynamic aspects of a reaction can help optimize conditions for maximum productivity in chemical processes. This knowledge is vital for predicting how oxidation states change in reactions and the energy implications involved.
Other exercises in this chapter
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