Textbook Question
The Kb for methylamine (CH3NH2) at 25 °C is given in Appendix D. (a) Write the chemical equation for the equilibrium that corresponds to Kb.
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Ch.19 - Chemical Thermodynamics
Chapter 19, Problem 85a
(a) Which of the thermodynamic quantities T, E, q, w, and S are state functions? (b) Which depend on the path taken from one state to another?
Verified step by step guidance1
Identify the definition of a state function: A state function is a property whose value does not depend on the path taken to reach that specific value. It depends only on the current state of the system.
List the given thermodynamic quantities: T (temperature), E (internal energy), q (heat), w (work), and S (entropy).
Determine which of these quantities are state functions: Temperature (T), internal energy (E), and entropy (S) are state functions because they depend only on the state of the system, not on how the system got to that state.
Identify which quantities depend on the path taken: Heat (q) and work (w) are not state functions because they depend on the specific path taken during a process.
Summarize: State functions (T, E, S) are independent of the path, while path functions (q, w) depend on the path taken between two states.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
State Functions
State functions are properties of a system that depend only on its current state, not on the path taken to reach that state. Examples include temperature (T), internal energy (E), enthalpy, and entropy (S). These quantities are useful in thermodynamics because they allow for the determination of system properties without needing to know the specific process involved.
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Logarithmic Functions
Path Functions
Path functions are properties that depend on the specific path taken during a process. Unlike state functions, their values change based on the route taken from one state to another. Heat (q) and work (w) are classic examples of path functions, as their values can vary significantly depending on the process used to transfer energy.
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Thermodynamic Processes
Thermodynamic processes describe the changes in a system's state due to energy transfer, which can occur as heat or work. Understanding these processes is crucial for distinguishing between state and path functions. For instance, in an isothermal process, temperature remains constant, while in an adiabatic process, no heat is exchanged, illustrating how different paths can affect energy transfer.
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Related Practice
Textbook Question
The Kb for methylamine (CH3NH2) at 25 °C is given in Appendix D. (d) What is the value of ΔG when [H+] = 6.7 × 10-9 M, [CH3NH3+] = 2.4 × 10-3 M, and [CH3NH2] = 0.098 M?
Open Question
(c) How many reversible paths are there between two states of a system?
Textbook Question
(d) For a reversible isothermal process, write an expression for ΔE in terms of q and w and an expression for ΔS in terms of q and T.
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Textbook Question
The crystalline hydrate Cd(NO3)2⋅4 H2O(s) loses water when placed in a large, closed, dry vessel at room temperature: Cd(NO3)2⋅4 H2O(s) → Cd(NO3)2(s) + 4 H2O(g) This process is spontaneous and ΔH° is positive at room temperature.
(a) What is the sign of ΔS° at room temperature?
Textbook Question
The crystalline hydrate Cd(NO3)2⋅4 H2O(s) loses water when placed in a large, closed, dry vessel at room temperature: Cd(NO3)2⋅4 H2O(s) → Cd(NO3)2(s) + 4 H2O(g) This process is spontaneous and ΔH° is positive at room temperature.
(b) If the hydrated compound is placed in a large, closed vessel that already contains a large amount of water vapor, does ΔS° change for this reaction at room temperature?
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