Question

Is \(\Delta S_{\text { surt }}\) favorable or unfavorable for exothermic reactions? Endothermic reactions? Explain.

Short answer

In summary, ΔS_surt is favorable (positive) for exothermic reactions, as they increase the disorder in the surroundings by releasing heat. On the other hand, ΔS_surt is unfavorable (negative) for endothermic reactions, as they decrease the disorder in the surroundings by absorbing heat.

Step-by-step solution

Understanding Entropy and Reaction Types

First, let's recall some key definitions: Entropy (S) is a measure of disorder or randomness in a system. Exothermic reactions are those that release heat to their surroundings (\(q < 0\)), while endothermic reactions absorb heat from their surroundings (\(q > 0\)). Now, let's analyze how ΔS_surt is affected by exothermic and endothermic reactions.

Exothermic Reactions and ΔS_surt

For exothermic reactions, heat is released into the surroundings, which usually leads to an increase in disorder or randomness. As a result, the entropy change ΔS_surt tends to be positive. A positive ΔS_surt means that the process is favorable from the standpoint of the surroundings' entropy.

Endothermic Reactions and ΔS_surt

For endothermic reactions, heat is absorbed from the surroundings, which usually results in a decrease in disorder or randomness. As a consequence, the entropy change ΔS_surt tends to be negative. A negative ΔS_surt implies that the process is unfavorable from the standpoint of the surroundings' entropy.

Conclusion

In conclusion, ΔS_surt is generally favorable (positive) for exothermic reactions, as they increase the disorder of the surroundings by releasing heat. Conversely, ΔS_surt is generally unfavorable (negative) for endothermic reactions, as they decrease the disorder of the surroundings by absorbing heat.

Key concepts

exothermic reactions

In the field of chemistry, understanding exothermic reactions is crucial. These reactions are characterized by the release of heat into the surroundings. When a chemical reaction occurs, it can either absorb or release energy. For exothermic reactions, this means that energy is released in the form of heat.
Here are some key points about exothermic reactions:

• They usually lead to an increase in the temperature of the surroundings.
• Common examples include combustion reactions, such as when wood burns in a fireplace.
• The system's enthalpy change (\( ext{ΔH}\)) for exothermic reactions is negative because heat exits the system.

As heat is released, the disorder or randomness in the surroundings increases. This means the entropy change (\( ext{ΔS}_{ ext{sur}}\)) for the surroundings is generally positive, indicating a favorable process for the surroundings.

endothermic reactions

Unlike exothermic reactions, endothermic reactions absorb heat from their surroundings. This absorption leads to a decrease in the temperature around the reaction site. Energy is taken in by the system, typically making it cooler.
Key ideas about endothermic reactions include:

• They tend to make the surroundings feel cooler as heat is absorbed.
• Endothermic processes include simple everyday examples, like the melting of ice.
• The enthalpy change (\( ext{ΔH}\)) for endothermic reactions is positive, a reflection of the system's intake of heat.

When the reaction absorbs heat, the disorder or randomness in the surroundings decreases. Hence, the entropy change (\( ext{ΔS}_{ ext{sur}}\)) is negative, suggesting that the process is generally unfavorable for the surroundings' entropy.

thermodynamics

Thermodynamics is a fundamental branch of physics and chemistry that deals with heat and temperature and their relation to energy and work. It is a key concept for understanding chemical reactions, particularly with enthalpy and entropy.
Some basic principles of thermodynamics include:

• The first law of thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed, only transformed.
• The second law of thermodynamics introduces the concept of entropy, explaining why certain processes occur spontaneously.
• Entropy is often associated with the disorder within a system. Systems tend to move towards greater entropy.

By studying thermodynamics, scientists can predict whether a reaction will be exothermic or endothermic, and understand why certain reactions are more favorable than others. The interplay of enthalpy, entropy, and free energy ultimately determines the spontaneity and favorability of chemical processes.