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Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145당신이 사용하는 게 아니라요?교과서 변경
18장, 문제 26

Consider the gas-phase reaction of AB3 and A2 molecules: Molecular representation of AB3 and A2 in a gas-phase reaction for entropy analysis.
(a) Write a balanced equation for the reaction. (b) What is the sign of the entropy change for the reaction?

검증된 단계별 안내
1
Identify the reactants and products in the given image. The left side shows AB3 and A2 molecules, and the right side shows the products of the reaction.
Count the number of each type of molecule on both sides of the reaction. On the left, there are 6 AB3 molecules and 3 A2 molecules. On the right, there are 6 A2B3 molecules.
Write the balanced chemical equation for the reaction. Ensure that the number of atoms of each element is the same on both sides of the equation.
Determine the change in the number of gas molecules from reactants to products. Compare the total number of gas molecules on the reactant side with the total number on the product side.
Analyze the entropy change (ΔS) for the reaction. If the number of gas molecules decreases, the entropy change is negative (ΔS < 0). If the number of gas molecules increases, the entropy change is positive (ΔS > 0).

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영상 길이:
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction with equal numbers of each type of atom on both sides of the equation. This ensures the law of conservation of mass is upheld, meaning that matter is neither created nor destroyed during the reaction. In this case, the reaction involves the combination of AB3 and A2, and the balanced equation will reflect the stoichiometry of the reactants and products.
추천 영상:
가이드 코스
01:32
Balancing Chemical Equations

Entropy Change (ΔS)

Entropy (S) is a measure of the disorder or randomness in a system. The change in entropy (ΔS) during a reaction indicates whether the disorder of the system increases or decreases. In gas-phase reactions, an increase in the number of gas molecules typically leads to a positive ΔS, while a decrease results in a negative ΔS. Understanding the molecular arrangement before and after the reaction is crucial for determining the sign of ΔS.
추천 영상:
가이드 코스
01:46
Entropy in Phase Changes

Molecular Representation and Reaction Dynamics

Molecular representation visually depicts the arrangement and interaction of molecules in a reaction. Analyzing these representations helps in understanding how reactants transform into products, including changes in molecular structure and the number of molecules involved. In the provided image, the arrangement of AB3 and A2 molecules can provide insights into the potential changes in entropy and the balanced equation for the reaction.
추천 영상:
가이드 코스
01:31
Molecularity in Reactions
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교과서 질문
Consider the following graph of total free energy of reactants and products versus reaction progress for the general reaction, Reactants -> Products. At which of the four points (labeled a, b, c, and d) is Q < K?

(a) Point a (b) Point c and d (c) Point a, c, and d (d) Point b
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교과서 질문

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(b) What are the signs ( + , - , or 0) of ∆H, ∆S, and ∆G for this process? Explain.

280
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교과서 질문

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(a) Sketch the final (equilibrium) state of the system.

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교과서 질문

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(c) How dpes this process illustrate the second law of thermodynamics?

326
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교과서 질문

Formation constants for the ammonia and ethylenediamine complexes of nickel(II) indicate that Ni(en)32+ is much more

stable than Ni(NH3)62+:

(1) <REACTION>

(2) <REACTION>

The enthalpy changes for the two reactions, ΔH°1 and ΔH°2, should be about the same because both complexes have six Ni﹣N bonds. 

(c) Assuming that ΔH°2 - ΔH°1 is zero, calculate the value of ΔS°2 - ΔS°1.

100
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교과서 질문

Spinach contains a lot of iron but is not a good source of dietary iron because nearly all the iron is tied up in the oxalate complex [Fe(C2O4)3]3-.

(b) Under the acidic conditions in the stomach, the Fe3+ concentration should be greater because of the reaction

[Fe(C2O4)3]3-(aq) + 6 H3O+(aq) ⇌ Fe3+(aq) + 3 H2C2O4(aq) + 6 H2O(l)

Show, however, that this reaction is nonspontaneous under standard-state conditions. (For H2C2O4, Ka1 = 5.9 × 10-2 and Ka2 = 6.4 × 10-5.)

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