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Ch.19 - Electrochemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145당신이 사용하는 게 아니라요?교과서 변경
19장, 문제 109

If a reaction has an equilibrium constant K 6 1, is E° posi-tive or negative? What is the value of K when E° = 0 V?

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insert step 1> Start by recalling the relationship between the equilibrium constant (K) and the standard cell potential (E°) given by the Nernst equation: E° = (RT/nF) * ln(K), where R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, and F is Faraday's constant.
insert step 2> Understand that if K > 1, the reaction favors the formation of products at equilibrium, which typically corresponds to a positive E° value, indicating a spontaneous reaction under standard conditions.
insert step 3> Conversely, if K < 1, the reaction favors the reactants, which typically corresponds to a negative E° value, indicating a non-spontaneous reaction under standard conditions.
insert step 4> For the second part of the question, when E° = 0 V, the reaction is at equilibrium under standard conditions, meaning there is no net tendency for the reaction to proceed in either direction.
insert step 5> Therefore, when E° = 0 V, the equilibrium constant K is equal to 1, indicating that the concentrations of reactants and products are equal at equilibrium.

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주요 개념

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

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. A K value greater than 1 indicates that products are favored at equilibrium, while a K value less than 1 suggests that reactants are favored. Understanding K is crucial for predicting the direction of a reaction and its extent.
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가이드 코스
01:14
Equilibrium Constant K

Standard Electrode Potential (E°)

Standard electrode potential (E°) is a measure of the tendency of a chemical species to be reduced, expressed in volts. A positive E° indicates a greater likelihood of reduction, while a negative E° suggests a tendency towards oxidation. The relationship between E° and K is described by the Nernst equation, which connects thermodynamics and electrochemistry.
추천 영상:
가이드 코스
01:27
Standard Cell Potential

Nernst Equation

The Nernst equation relates the standard electrode potential (E°) to the equilibrium constant (K) and the concentrations of reactants and products. It shows that when E° is positive, K is greater than 1, and when E° is negative, K is less than 1. At E° = 0 V, the equation indicates that K equals 1, meaning the concentrations of reactants and products are equal at equilibrium.
추천 영상:
가이드 코스
01:17
The Nernst Equation