(a) What do you expect for the sign of ΔS in a chemical reaction in which 2 mol of gaseous reactants are converted to 3 mol of gaseous products? (b) For which of the processes in Exercise 19.11 does the entropy of the system increase?

Verified step by step guidance

1. Step 1: Understand the concept of entropy (ΔS). Entropy is a measure of the disorder or randomness in a system. In general, the more disordered a system, the higher its entropy.
2. Step 2: Analyze part (a) of the problem. Consider the change in the number of moles of gas in the reaction. Going from 2 moles of gaseous reactants to 3 moles of gaseous products suggests an increase in disorder, as more gas molecules typically mean more possible arrangements and higher entropy.
3. Step 3: Predict the sign of ΔS for part (a). Since the number of moles of gas increases, the entropy of the system is expected to increase, indicating a positive ΔS.
4. Step 4: For part (b), review Exercise 19.11 to identify processes. Look for processes where the system becomes more disordered, such as phase changes from solid to liquid or liquid to gas, or reactions where the number of gas molecules increases.
5. Step 5: Determine which processes in Exercise 19.11 lead to an increase in entropy. Focus on those that involve an increase in the number of gas molecules or transitions to more disordered states.

Key Concepts

Entropy (ΔS)

Entropy, denoted as ΔS, is a measure of the disorder or randomness in a system. In chemical reactions, an increase in the number of gas molecules typically leads to an increase in entropy, as more particles can occupy more microstates. Therefore, when 2 moles of gaseous reactants convert to 3 moles of gaseous products, we expect ΔS to be positive, indicating an increase in disorder.

Gaseous Reactants and Products

Gaseous reactants and products play a crucial role in determining the change in entropy during a reaction. The transition from fewer gas molecules to more gas molecules generally results in a greater number of possible arrangements and configurations, thus increasing the system's entropy. This concept is essential for predicting the sign of ΔS in reactions involving gases.

Thermodynamic Processes and Entropy Changes

Different thermodynamic processes can lead to varying changes in entropy. For example, processes that involve phase changes, mixing of substances, or reactions that produce more gas molecules typically result in an increase in entropy. Analyzing specific processes, such as those in Exercise 19.11, requires understanding how these factors influence the overall entropy of the system.