Based On The Equation And The Information In The Table, What Is The Enthalpy Of The Reaction?Given Reaction: $\[ N_2(g) + 3 H_2(g) \rightarrow 2 NH_3(g) \\]Standard Enthalpies Of Formation:\begin{tabular}{|c|c|}\hline Substance & $\Delta

Understanding Enthalpy and Its Importance

Enthalpy is a thermodynamic property that represents the total energy of a system, including its internal energy and the energy associated with the pressure and volume of a system. It is a crucial concept in chemistry, as it helps us understand the energy changes that occur during chemical reactions. In this article, we will explore how to calculate the enthalpy of a chemical reaction using the equation and the standard enthalpies of formation.

The Equation and Standard Enthalpies of Formation

The given reaction is:

$$N_2(g) + 3 H_2(g) \rightarrow 2 NH_3(g)$$

The standard enthalpies of formation for the substances involved in the reaction are:

Substance	$\Delta H_f^{\circ}$ (kJ/mol)
$N_2(g)$	0
$H_2(g)$	0
$NH_3(g)$	-45.9

Calculating the Enthalpy of the Reaction

To calculate the enthalpy of the reaction, we need to use the following equation:

$$\Delta H_{rxn}^{\circ} = \sum \Delta H_f^{\circ} (\text{products}) - \sum \Delta H_f^{\circ} (\text{reactants})$$

where $\Delta H_{rxn}^{\circ}$ is the standard enthalpy of the reaction, and $\Delta H_f^{\circ}$ is the standard enthalpy of formation of each substance.

Step 1: Calculate the Enthalpy of Formation of the Products

The products of the reaction are 2 moles of $NH_3(g)$. Therefore, we need to calculate the enthalpy of formation of 2 moles of $NH_3(g)$.

$$\Delta H_f^{\circ} (\text{products}) = 2 \times \Delta H_f^{\circ} (NH_3(g))$$

$$\Delta H_f^{\circ} (\text{products}) = 2 \times -45.9$$

$$\Delta H_f^{\circ} (\text{products}) = -91.8$$

Step 2: Calculate the Enthalpy of Formation of the Reactants

The reactants of the reaction are 1 mole of $N_2(g)$ and 3 moles of $H_2(g)$. Therefore, we need to calculate the enthalpy of formation of 1 mole of $N_2(g)$ and 3 moles of $H_2(g)$.

$$\Delta H_f^{\circ} (\text{reactants}) = \Delta H_f^{\circ} (N_2(g)) + 3 \times \Delta H_f^{\circ} (H_2(g))$$

$$\Delta H_f^{\circ} (\text{reactants}) = 0 + 3 \times 0$$

$$\Delta H_f^{\circ} (\text{reactants}) = 0$$

Step 3: Calculate the Enthalpy of the Reaction

Now that we have calculated the enthalpy of formation of the products and the reactants, we can calculate the enthalpy of the reaction using the following equation:

$$\Delta H_{rxn}^{\circ} = \Delta H_f^{\circ} (\text{products}) - \Delta H_f^{\circ} (\text{reactants})$$

$$\Delta H_{rxn}^{\circ} = -91.8 - 0$$

$$\Delta H_{rxn}^{\circ} = -91.8$$

Conclusion

In this article, we have calculated the enthalpy of a chemical reaction using the equation and the standard enthalpies of formation. We have shown that the enthalpy of the reaction is -91.8 kJ/mol. This value represents the energy change that occurs during the reaction, and it can be used to predict the spontaneity of the reaction.

Importance of Enthalpy in Chemistry

Enthalpy is a crucial concept in chemistry, as it helps us understand the energy changes that occur during chemical reactions. It is used to predict the spontaneity of reactions, and it can be used to calculate the energy required to perform a reaction. In addition, enthalpy is used to calculate the energy released during a reaction, which is known as the heat of reaction.

Real-World Applications of Enthalpy

Enthalpy has many real-world applications in chemistry. For example, it is used to calculate the energy required to perform a reaction, which is known as the heat of reaction. It is also used to predict the spontaneity of reactions, which is important in many industrial processes. In addition, enthalpy is used to calculate the energy released during a reaction, which is known as the heat of reaction.

Limitations of Enthalpy

While enthalpy is a useful concept in chemistry, it has some limitations. For example, it does not take into account the entropy of a system, which is an important factor in determining the spontaneity of a reaction. In addition, enthalpy is not a state function, which means that it depends on the path taken to reach a particular state.

Conclusion

Q: What is enthalpy?

A: Enthalpy is a thermodynamic property that represents the total energy of a system, including its internal energy and the energy associated with the pressure and volume of a system.

Q: Why is enthalpy important in chemistry?

A: Enthalpy is important in chemistry because it helps us understand the energy changes that occur during chemical reactions. It is used to predict the spontaneity of reactions, and it can be used to calculate the energy required to perform a reaction.

Q: How is enthalpy calculated?

A: Enthalpy is calculated using the following equation:

$$\Delta H_{rxn}^{\circ} = \sum \Delta H_f^{\circ} (\text{products}) - \sum \Delta H_f^{\circ} (\text{reactants})$$

where $\Delta H_{rxn}^{\circ}$ is the standard enthalpy of the reaction, and $\Delta H_f^{\circ}$ is the standard enthalpy of formation of each substance.

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

A: Enthalpy is the total energy of a system, including its internal energy and the energy associated with the pressure and volume of a system. Internal energy, on the other hand, is the energy of a system that is not associated with the pressure and volume of the system.

Q: Can enthalpy be negative?

A: Yes, enthalpy can be negative. A negative enthalpy value indicates that the reaction is exothermic, meaning that it releases energy.

Q: Can enthalpy be positive?

A: Yes, enthalpy can be positive. A positive enthalpy value indicates that the reaction is endothermic, meaning that it absorbs energy.

Q: What is the relationship between enthalpy and entropy?

A: Enthalpy and entropy are related in that a reaction with a high entropy change is more likely to be spontaneous than a reaction with a low entropy change.

Q: Can enthalpy be used to predict the spontaneity of a reaction?

A: Yes, enthalpy can be used to predict the spontaneity of a reaction. A negative enthalpy value indicates that the reaction is spontaneous, while a positive enthalpy value indicates that the reaction is non-spontaneous.

Q: What are some real-world applications of enthalpy?

A: Enthalpy has many real-world applications in chemistry, including:

• Calculating the energy required to perform a reaction
• Predicting the spontaneity of reactions
• Calculating the energy released during a reaction
• Designing chemical processes and equipment

Q: What are some limitations of enthalpy?

A: Some limitations of enthalpy include:

• It does not take into account the entropy of a system
• It is not a state function, meaning that it depends on the path taken to reach a particular state

Q: Can enthalpy be used to calculate the energy required to perform a reaction?

A: Yes, enthalpy can be used to calculate the energy required to perform a reaction. This is known as the heat of reaction.

Q: Can enthalpy be used to calculate the energy released during a reaction?

A: Yes, enthalpy can be used to calculate the energy released during a reaction. This is known as the heat of reaction.

Conclusion

In conclusion, enthalpy is a crucial concept in chemistry that helps us understand the energy changes that occur during chemical reactions. It is used to predict the spontaneity of reactions, and it can be used to calculate the energy required to perform a reaction. While enthalpy has some limitations, it remains an important tool in chemistry.