Importance of Enthalpy Change

Oct 13, 2025 by magicalceylontours.com 90 views

Understanding the Problem

To solve this problem, we need to understand the concept of enthalpy change and how it relates to the formation of carbon dioxide ( $CO_2$ ). Enthalpy change is a measure of the energy change that occurs during a chemical reaction. It can be either positive or negative, depending on whether the reaction releases or absorbs energy.

Formation of $CO_2$

The formation of $CO_2$ from carbon ( $C$ ) and oxygen ( $O_2$ ) is a highly exothermic reaction, meaning that it releases a significant amount of energy. This energy is released in the form of heat, which is why the reaction is often used to produce steam in power plants.

Enthalpy Change

The enthalpy change ( $\Delta H$ ) is a measure of the energy change that occurs during a chemical reaction. It is defined as the difference between the enthalpy of the products and the enthalpy of the reactants. In the case of the formation of $CO_2$ , the enthalpy change is negative, indicating that the reaction releases energy.

Analyzing the Options

Now, let's analyze the two options given:

Option A: $C(s) + O_2(g) \rightarrow CO_2(g) + 393.5 \, \text{kJ}$

In this option, the reaction is written as:

C(s) + O_2(g) \rightarrow CO_2(g) + 393.5 \, \text{kJ}

The enthalpy change is given as $393.5 \, \text{kJ}$ , which is a positive value. However, this is not the correct way to represent the enthalpy change. The correct way to represent the enthalpy change is to use the $\Delta H$ symbol, like this:

\Delta H = -393.5 \, \text{kJ/mol}

The negative sign indicates that the reaction releases energy.

Option B: $C(s) + O_2(g) + 393.5 \, \text{kJ} \rightarrow CO_2(g)$

In this option, the reaction is written as:

C(s) + O_2(g) + 393.5 \, \text{kJ} \rightarrow CO_2(g)

The enthalpy change is not explicitly given, but we can infer that it is positive, since the reaction is written as an addition of energy to the reactants.

Conclusion

Based on our analysis, we can conclude that the correct answer is Option A. The reaction is written as:

C(s) + O_2(g) \rightarrow CO_2(g) + 393.5 \, \text{kJ}

However, the enthalpy change is not correctly represented. The correct way to represent the enthalpy change is to use the $\Delta H$ symbol, like this:

\Delta H = -393.5 \, \text{kJ/mol}

This indicates that the reaction releases $393.5 \, \text{kJ/mol}$ of energy.

Importance of Enthalpy Change

The enthalpy change is an important concept in chemistry, as it helps us understand the energy changes that occur during chemical reactions. In the case of the formation of $CO_2$ , the enthalpy change is negative, indicating that the reaction releases energy. This energy can be harnessed to produce steam in power plants, which is then used to generate electricity.

Real-World Applications

The formation of $CO_2$ has many real-world applications, including:

Power generation: The formation of $CO_2$ is used to produce steam in power plants, which is then used to generate electricity.
Industrial processes: The formation of $CO_2$ is used in various industrial processes, such as the production of chemicals and fuels.
Environmental applications: The formation of $CO_2$ is used in various environmental applications, such as the removal of carbon dioxide from the atmosphere.

Conclusion

In conclusion, the correct answer is Option A, but with the correct representation of the enthalpy change. The reaction is written as:

C(s) + O_2(g) \rightarrow CO_2(g) + 393.5 \, \text{kJ}

However, the enthalpy change is not correctly represented. The correct way to represent the enthalpy change is to use the $\Delta H$ symbol, like this:

\Delta H = -393.5 \, \text{kJ/mol}

This indicates that the reaction releases $393.5 \, \text{kJ/mol}$ of energy.

References

CRC Handbook of Chemistry and Physics, 97th ed. (2016).
Kittel, C. (2005). Introduction to Solid State Physics. Wiley.
Levine, I. N. (2008). Physical Chemistry. McGraw-Hill.

Glossary

Enthalpy change: The energy change that occurs during a chemical reaction.
$\Delta H$ : The symbol used to represent the enthalpy change.
$CO_2$ : Carbon dioxide.
$C(s)$ : Carbon in its solid state.
$O_2(g)$ : Oxygen in its gaseous state.

Understanding Enthalpy Change

Enthalpy change is a measure of the energy change that occurs during a chemical reaction. It can be either positive or negative, depending on whether the reaction releases or absorbs energy. In the case of the formation of $CO_2$ , the enthalpy change is negative, indicating that the reaction releases energy.

Q: What is the significance of enthalpy change in chemistry?

A: Enthalpy change is an important concept in chemistry, as it helps us understand the energy changes that occur during chemical reactions. It can be used to predict the spontaneity of a reaction, as well as the amount of energy released or absorbed during the reaction.

Q: How is enthalpy change represented in a chemical equation?

A: Enthalpy change is represented in a chemical equation using the $\Delta H$ symbol. For example, the equation for the formation of $CO_2$ is:

C(s) + O_2(g) \rightarrow CO_2(g) + \Delta H

The $\Delta H$ symbol represents the enthalpy change, which is a measure of the energy change that occurs during the reaction.

Q: What is the difference between enthalpy change and internal energy change?

A: Enthalpy change ( $\Delta H$ ) and internal energy change ( $\Delta U$ ) are related but distinct concepts. Enthalpy change is a measure of the energy change that occurs during a chemical reaction, while internal energy change is a measure of the energy change that occurs within the system itself.

Q: How is the enthalpy change of a reaction calculated?

A: The enthalpy change of a reaction can be calculated using the following equation:

\Delta H = \sum n\Delta H_f^{\circ}(\text{products}) - \sum n\Delta H_f^{\circ}(\text{reactants})

where $\Delta H_f^{\circ}$ is the standard enthalpy of formation of a substance, and $n$ is the number of moles of that substance.

Q: What is the standard enthalpy of formation?

A: The standard enthalpy of formation ( $\Delta H_f^{\circ}$ ) is the enthalpy change that occurs when one mole of a substance is formed from its constituent elements in their standard states.

Q: How is the standard enthalpy of formation used in calculations?

A: The standard enthalpy of formation is used in calculations to determine the enthalpy change of a reaction. It is typically listed in a table of standard enthalpies of formation, and can be used to calculate the enthalpy change of a reaction using the equation above.

Q: What is the relationship between enthalpy change and temperature?

A: Enthalpy change is related to temperature, as the enthalpy change of a reaction can be affected by changes in temperature. In general, an increase in temperature will increase the enthalpy change of a reaction, while a decrease in temperature will decrease the enthalpy change.

Q: How is the enthalpy change of a reaction affected by pressure?

A: The enthalpy change of a reaction is not directly affected by pressure, as enthalpy change is a measure of the energy change that occurs during a chemical reaction, rather than a measure of the pressure of the system.

Q: What is the significance of the enthalpy change of the formation of $CO_2$ ?

A: The enthalpy change of the formation of $CO_2$ is significant, as it indicates that the reaction releases energy. This energy can be harnessed to produce steam in power plants, which is then used to generate electricity.

Q: How is the enthalpy change of the formation of $CO_2$ used in real-world applications?

A: The enthalpy change of the formation of $CO_2$ is used in various real-world applications, including:

Power generation: The formation of $CO_2$ is used to produce steam in power plants, which is then used to generate electricity.
Industrial processes: The formation of $CO_2$ is used in various industrial processes, such as the production of chemicals and fuels.
Environmental applications: The formation of $CO_2$ is used in various environmental applications, such as the removal of carbon dioxide from the atmosphere.

References

CRC Handbook of Chemistry and Physics, 97th ed. (2016).
Kittel, C. (2005). Introduction to Solid State Physics. Wiley.
Levine, I. N. (2008). Physical Chemistry. McGraw-Hill.

Glossary

Enthalpy change: The energy change that occurs during a chemical reaction.
$\Delta H$ : The symbol used to represent the enthalpy change.
$CO_2$ : Carbon dioxide.
$C(s)$ : Carbon in its solid state.
$O_2(g)$ : Oxygen in its gaseous state.
Standard enthalpy of formation: The enthalpy change that occurs when one mole of a substance is formed from its constituent elements in their standard states.