Given The Overall Chemical Equation:${ C (s) + H_2O (g) \rightarrow CO (g) + H_2(g) }$To Calculate The Final Enthalpy Equation, Which Step Must Occur?A. Reverse The First Equation, And Change The Sign Of The Enthalpy. Then, Add.B. Reverse

Understanding the Basics of Enthalpy Equations

Enthalpy equations are a crucial concept in chemistry, used to calculate the energy changes that occur during chemical reactions. Given a chemical equation, we can determine the enthalpy change by using the following steps. In this article, we will explore the process of calculating the final enthalpy equation for a given chemical reaction.

The Given Chemical Equation

The given chemical equation is:

${ C (s) + H_2O (g) \rightarrow CO (g) + H_2(g) }$

This equation represents a reaction between carbon (C) and water vapor (H2O) to produce carbon monoxide (CO) and hydrogen gas (H2).

Calculating the Final Enthalpy Equation

To calculate the final enthalpy equation, we need to follow a specific step. The correct step is:

A. Reverse the first equation, and change the sign of the enthalpy. Then, add.

Why Reverse the Equation?

Reversing the equation is necessary because we want to calculate the enthalpy change for the reverse reaction. By reversing the equation, we are essentially flipping the direction of the reaction.

Why Change the Sign of the Enthalpy?

Changing the sign of the enthalpy is necessary because the enthalpy change for the reverse reaction is the negative of the enthalpy change for the original reaction. This is a fundamental principle in chemistry, and it is essential to understand this concept when working with enthalpy equations.

Why Add the Reversed Equation?

Adding the reversed equation is necessary because we want to calculate the enthalpy change for the overall reaction. By adding the reversed equation, we are essentially combining the two reactions to get the overall reaction.

Example: Calculating the Final Enthalpy Equation

Let's consider an example to illustrate the process of calculating the final enthalpy equation.

Suppose we have the following enthalpy equation for the original reaction:

${ C (s) + H_2O (g) \rightarrow CO (g) + H_2(g) }$ ${ \Delta H = -131.3 \, kJ/mol }$

To calculate the final enthalpy equation, we need to reverse the equation and change the sign of the enthalpy:

${ CO (g) + H_2(g) \rightarrow C (s) + H_2O (g) }$ ${ \Delta H = 131.3 \, kJ/mol }$

Then, we add the reversed equation to get the overall reaction:

${ C (s) + H_2O (g) \rightarrow CO (g) + H_2(g) }$ ${ \Delta H = 0 \, kJ/mol }$

Conclusion

In conclusion, to calculate the final enthalpy equation, we need to reverse the first equation, change the sign of the enthalpy, and then add. This process is essential in chemistry, and it helps us understand the energy changes that occur during chemical reactions.

Key Takeaways

• Reversing the equation is necessary to calculate the enthalpy change for the reverse reaction.
• Changing the sign of the enthalpy is necessary because the enthalpy change for the reverse reaction is the negative of the enthalpy change for the original reaction.
• Adding the reversed equation is necessary to calculate the enthalpy change for the overall reaction.

References

• Atkins, P. W., & de Paula, J. (2010). Physical chemistry (9th ed.). Oxford University Press.
• Chang, R. (2010). Chemistry (10th ed.). McGraw-Hill.

Further Reading

• Enthalpy equations: A comprehensive guide
• Calculating enthalpy changes: A step-by-step guide
• Understanding the basics of thermodynamics
  Frequently Asked Questions: Calculating the Final Enthalpy Equation ====================================================================

Q: What is the purpose of reversing the equation when calculating the final enthalpy equation?

A: Reversing the equation is necessary to calculate the enthalpy change for the reverse reaction. By reversing the equation, we are essentially flipping the direction of the reaction.

Q: Why do we need to change the sign of the enthalpy when calculating the final enthalpy equation?

A: We need to change the sign of the enthalpy because the enthalpy change for the reverse reaction is the negative of the enthalpy change for the original reaction. This is a fundamental principle in chemistry, and it is essential to understand this concept when working with enthalpy equations.

Q: What is the difference between the enthalpy change for the original reaction and the enthalpy change for the reverse reaction?

A: The enthalpy change for the original reaction is the energy change that occurs during the forward reaction, while the enthalpy change for the reverse reaction is the energy change that occurs during the reverse reaction. The enthalpy change for the reverse reaction is the negative of the enthalpy change for the original reaction.

Q: How do we calculate the final enthalpy equation for a given chemical reaction?

A: To calculate the final enthalpy equation, we need to follow the following steps:

1. Reverse the first equation.
2. Change the sign of the enthalpy.
3. Add the reversed equation.

Q: What is the significance of the final enthalpy equation in chemistry?

A: The final enthalpy equation is a crucial concept in chemistry, as it helps us understand the energy changes that occur during chemical reactions. By calculating the final enthalpy equation, we can determine the energy change that occurs during a reaction, which is essential in understanding the thermodynamics of a reaction.

Q: Can we calculate the final enthalpy equation for any chemical reaction?

A: Yes, we can calculate the final enthalpy equation for any chemical reaction. However, we need to ensure that we have the correct enthalpy values for the original reaction and the reverse reaction.

Q: What are some common mistakes to avoid when calculating the final enthalpy equation?

A: Some common mistakes to avoid when calculating the final enthalpy equation include:

• Not reversing the equation correctly.
• Not changing the sign of the enthalpy correctly.
• Not adding the reversed equation correctly.

Q: How can we verify the accuracy of the final enthalpy equation?

A: We can verify the accuracy of the final enthalpy equation by checking the units and the sign of the enthalpy change. We can also use thermodynamic tables or databases to verify the accuracy of the enthalpy values.

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

A: The final enthalpy equation has many real-world applications, including:

• Calculating the energy required for a reaction.
• Determining the feasibility of a reaction.
• Understanding the thermodynamics of a reaction.

Conclusion

In conclusion, the final enthalpy equation is a crucial concept in chemistry, and it is essential to understand how to calculate it correctly. By following the steps outlined in this article, we can calculate the final enthalpy equation for any chemical reaction.