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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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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.

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.

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.

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Copper reduces dilute nitric acid to nitric oxide (NO) but reduces concentrated nitric acid to nitrogen dioxide (NO2): Assuming that [Cu2+] = 0.10 M and that the partial pressures of NO and NO2 are 1.0 * 10-3 atm, calculate the potential (E) for reactions (1) and (2) at 25 °C and show which reaction has the greater thermodynamic tendency to occur when the concentration of HNO3 is(a) 1.0 M

Textbook Question

What is the pH of the solution in the cathode compartment of the following cell if the measured cell potential at 25 °C is 0.17 V?

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Textbook Question

Beginning with the equations that relate E°, ∆G°, and K, show that ∆G° is negative and K 7 1 for a reaction that has a positive value of E°

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