Calculate Δ S R X N \Delta S_{rxn} Δ S R X N ​ For This Equation. Round To The Nearest Whole Number.$[ \begin{array}{l} \text{NaOH(aq) + HCl(aq) } \rightarrow \text{ H} 2\text{O(l) + NaCl(aq)} \ S {\text{NaOH}} = 49.8 , \text{J/mol K} \ S_{\text{HCl}} =

Introduction

Entropy is a measure of disorder or randomness in a system. In the context of chemical reactions, entropy change is an important factor in determining the spontaneity of a reaction. The change in entropy of a reaction, denoted by $\Delta S_{rxn}$, is calculated by subtracting the sum of the entropies of the reactants from the sum of the entropies of the products. In this article, we will calculate the change in entropy for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl).

The Reaction Equation

The reaction equation is given as:

$\text{NaOH(aq) + HCl(aq) } \rightarrow \text{ H}_2\text{O(l) + NaCl(aq)}$

Entropy Values

The entropy values for the reactants and products are given as:

• $S_{\text{NaOH}} = 49.8 \, \text{J/mol K}$
• $S_{\text{HCl}} = 56.5 \, \text{J/mol K}$
• $S_{\text{H}_2\text{O}} = 70.0 \, \text{J/mol K}$
• $S_{\text{NaCl}} = 109.2 \, \text{J/mol K}$

Calculating the Change in Entropy

To calculate the change in entropy, we need to subtract the sum of the entropies of the reactants from the sum of the entropies of the products.

$\Delta S_{rxn} = S_{\text{products}} - S_{\text{reactants}}$

The sum of the entropies of the products is:

$S_{\text{products}} = S_{\text{H}_2\text{O}} + S_{\text{NaCl}} = 70.0 \, \text{J/mol K} + 109.2 \, \text{J/mol K} = 179.2 \, \text{J/mol K}$

The sum of the entropies of the reactants is:

$S_{\text{reactants}} = S_{\text{NaOH}} + S_{\text{HCl}} = 49.8 \, \text{J/mol K} + 56.5 \, \text{J/mol K} = 106.3 \, \text{J/mol K}$

Now, we can calculate the change in entropy:

$\Delta S_{rxn} = S_{\text{products}} - S_{\text{reactants}} = 179.2 \, \text{J/mol K} - 106.3 \, \text{J/mol K} = 72.9 \, \text{J/mol K}$

Rounding to the Nearest Whole Number

The change in entropy is calculated to be $72.9 \, \text{J/mol K}$. Rounding to the nearest whole number, we get:

$\Delta S_{rxn} = 73 \, \text{J/mol K}$

Conclusion

In this article, we calculated the change in entropy for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl). The change in entropy was calculated to be $72.9 \, \text{J/mol K}$, which rounds to the nearest whole number as $73 \, \text{J/mol K}$. This value can be used to determine the spontaneity of the reaction and to predict the direction of the reaction.

Entropy and Spontaneity

Entropy is a measure of disorder or randomness in a system. In the context of chemical reactions, entropy change is an important factor in determining the spontaneity of a reaction. A positive change in entropy indicates an increase in disorder or randomness, while a negative change in entropy indicates a decrease in disorder or randomness.

Entropy and Reaction Direction

The direction of a reaction can be predicted by considering the change in entropy. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Entropy and Equilibrium

At equilibrium, the change in entropy is zero. This means that the disorder or randomness of the system is at a maximum, and there is no net change in entropy.

Entropy and Temperature

Entropy is a function of temperature. As the temperature increases, the disorder or randomness of a system also increases. This means that the change in entropy is also a function of temperature.

Entropy and Entropy Units

Entropy is typically measured in units of joules per mole per kelvin (J/mol K). This unit represents the change in entropy per mole of substance per kelvin of temperature.

Entropy and Entropy Calculations

Entropy calculations involve the use of entropy values for the reactants and products. These values are typically obtained from thermodynamic tables or calculated using statistical mechanics.

Entropy and Reaction Equilibrium

At reaction equilibrium, the change in entropy is zero. This means that the disorder or randomness of the system is at a maximum, and there is no net change in entropy.

Entropy and Reaction Spontaneity

The spontaneity of a reaction can be predicted by considering the change in entropy. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Entropy and Reaction Direction

The direction of a reaction can be predicted by considering the change in entropy. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Entropy and Reaction Equilibrium

At reaction equilibrium, the change in entropy is zero. This means that the disorder or randomness of the system is at a maximum, and there is no net change in entropy.

Entropy and Reaction Spontaneity

The spontaneity of a reaction can be predicted by considering the change in entropy. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Entropy and Reaction Direction

Q: What is entropy?

A: Entropy is a measure of disorder or randomness in a system. It is a thermodynamic property that can be used to predict the spontaneity of a reaction and the direction of a reaction.

Q: What is the unit of entropy?

A: The unit of entropy is joules per mole per kelvin (J/mol K). This unit represents the change in entropy per mole of substance per kelvin of temperature.

Q: How is entropy calculated?

A: Entropy is calculated by subtracting the sum of the entropies of the reactants from the sum of the entropies of the products. The entropy values for the reactants and products are typically obtained from thermodynamic tables or calculated using statistical mechanics.

Q: What is the significance of entropy in chemistry?

A: Entropy is an important factor in determining the spontaneity of a reaction and the direction of a reaction. A positive change in entropy indicates an increase in disorder or randomness, while a negative change in entropy indicates a decrease in disorder or randomness.

Q: Can entropy be negative?

A: Yes, entropy can be negative. A negative change in entropy indicates a decrease in disorder or randomness.

Q: What is the relationship between entropy and temperature?

A: Entropy is a function of temperature. As the temperature increases, the disorder or randomness of a system also increases.

Q: What is the relationship between entropy and reaction equilibrium?

A: At reaction equilibrium, the change in entropy is zero. This means that the disorder or randomness of the system is at a maximum, and there is no net change in entropy.

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

A: Yes, entropy can be used to predict the spontaneity of a reaction. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Q: Can entropy be used to predict the direction of a reaction?

A: Yes, entropy can be used to predict the direction of a reaction. If the change in entropy is positive, the reaction will tend to proceed in the forward direction, while if the change in entropy is negative, the reaction will tend to proceed in the reverse direction.

Q: What is the relationship between entropy and Gibbs free energy?

A: The Gibbs free energy is a measure of the energy available to do work in a system. Entropy is a component of the Gibbs free energy equation, and it can be used to predict the spontaneity of a reaction.

Q: Can entropy be used to predict the stability of a system?

A: Yes, entropy can be used to predict the stability of a system. A system with a high entropy is more stable than a system with a low entropy.

Q: Can entropy be used to predict the rate of a reaction?

A: Yes, entropy can be used to predict the rate of a reaction. A reaction with a high entropy will tend to proceed faster than a reaction with a low entropy.

Q: What is the relationship between entropy and the second law of thermodynamics?

A: The second law of thermodynamics states that the total entropy of a closed system will always increase over time. This means that the disorder or randomness of a system will always increase over time.

Q: Can entropy be used to predict the behavior of a system under different conditions?

A: Yes, entropy can be used to predict the behavior of a system under different conditions. By considering the change in entropy, we can predict how a system will behave under different conditions, such as changes in temperature or pressure.

Q: What is the significance of entropy in biology?

A: Entropy is an important factor in biology, particularly in the context of living systems. Living systems are characterized by a high degree of organization and a low degree of entropy. However, as living systems age, their entropy increases, leading to a decrease in their ability to function.

Q: Can entropy be used to predict the behavior of a living system?

A: Yes, entropy can be used to predict the behavior of a living system. By considering the change in entropy, we can predict how a living system will behave under different conditions, such as changes in temperature or pressure.

Q: What is the relationship between entropy and the concept of "death"?

A: The concept of "death" can be related to entropy. As living systems age, their entropy increases, leading to a decrease in their ability to function. Eventually, the entropy of a living system becomes so high that it can no longer function, leading to "death".

Q: Can entropy be used to predict the behavior of a system in a non-equilibrium state?

A: Yes, entropy can be used to predict the behavior of a system in a non-equilibrium state. By considering the change in entropy, we can predict how a system will behave under different conditions, such as changes in temperature or pressure.

Q: What is the significance of entropy in the context of the universe?

A: Entropy is an important factor in the context of the universe. The universe is characterized by a high degree of disorder or randomness, which is reflected in its high entropy. As the universe ages, its entropy will continue to increase, leading to a decrease in its ability to function.

Q: Can entropy be used to predict the behavior of the universe?

A: Yes, entropy can be used to predict the behavior of the universe. By considering the change in entropy, we can predict how the universe will behave under different conditions, such as changes in temperature or pressure.

Q: What is the relationship between entropy and the concept of "heat death"?

A: The concept of "heat death" can be related to entropy. As the universe ages, its entropy will continue to increase, leading to a decrease in its ability to function. Eventually, the entropy of the universe will become so high that it can no longer function, leading to "heat death".