Skip to main content
Ch.19 - Chemical Thermodynamics
Brown - Chemistry: The Central Science 15th Edition
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoBrown 15th EditionCh.19 - Chemical ThermodynamicsProblema 105a
Capitolo 19, Problema 105a

When most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here:
Suppose you stretch a rubber band. (a) Do you expect the entropy of the system to increase or decrease?

Guida verificata passo dopo passo
1
Understand the concept of entropy, which is a measure of the disorder or randomness in a system.
Recognize that when the rubber band is unstretched, the polymer molecules are in a tangled, disordered state.
Consider that stretching the rubber band aligns the polymer molecules, making them more ordered compared to their initial state.
Recall that an increase in order corresponds to a decrease in entropy according to the second law of thermodynamics.
Conclude whether the entropy of the rubber band increases or decreases based on the change in molecular order when stretched.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
33s

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Entropy

Entropy is a measure of the disorder or randomness in a system. In thermodynamics, it quantifies the number of possible arrangements of particles in a system. A higher entropy indicates a more disordered state, while lower entropy suggests a more ordered state. Understanding how entropy changes during physical processes is crucial for predicting the behavior of materials, such as elastomers.
Video consigliato:
Percorso guidato
02:46
Entropy in Thermodynamics

Molecular Order in Polymers

Polymers, like rubber, consist of long chains of repeating units. When stretched, the molecular chains align more closely, leading to increased order within the material. This alignment reduces the freedom of movement of the polymer chains, which can affect the overall entropy of the system. Recognizing how stretching influences molecular arrangement is key to understanding the thermodynamic properties of elastomers.
Video consigliato:
Percorso guidato
01:29
Bond Order Calculation

Thermodynamic Principles

Thermodynamic principles govern the behavior of energy and matter in systems. The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time. When analyzing the stretching of a rubber band, it is essential to consider how energy input (stretching) affects the system's entropy and whether the overall process leads to an increase or decrease in entropy.
Video consigliato:
Percorso guidato
01:18
First Law of Thermodynamics
Pratica correlata
Domanda del libro di testo

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (b) In principle, is this reaction a feasible method of removing SO2?

420
views
Domanda del libro di testo

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (a) What is the equilibrium constant for the reaction at 298 K? (c) If PSO2 = PH2S and the vapor pressure of water is 25 torr, calculate the equilibrium SO2 pressure in the system at 298 K.

488
views
Domanda del libro di testo

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (d) Would you expect the process to be more or less effective at higher temperatures?

339
views