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?

Verified step by step guidance

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.

Key Concepts

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.