Question

Using standard electrode potentials, calculate the standard free-energy change at 25°C for the following reaction.

3Cu(s) + 2NO³⁻ (aq) + 8H*(aq) → 3Cu²⁺(aq) + 2NO(g) + 4H₂O(1)

Answer 1

To find the standard free-energy change for a given reaction, one must calculate the standard electrode potentials of the half-reactions, derive the standard cell potential, and use these to determine the free-energy change and reaction spontaneity.

Step-by-step explanation:

The calculation of the standard free-energy change (ΔG°) for the given chemical reaction involves determining the standard electrode potentials for both the oxidation and reduction half-reactions. The reaction in question is as follows:

3Cu(s) + 2NO− + 8H+ (aq) → 3Cu2+(aq) + 2NO(g) + 4H2O(l)

To calculate ΔG° we use the following equations:

1. Find the standard reduction potential for both half-reactions.
   
2. Calculate the standard cell potential (E°cell) by subtracting the standard anode potential from the standard cathode potential.
3. Use the equation ΔG° = -nFE°cell, where n is the number of moles of electrons transferred, F is the Faraday constant (96485C/mol), and E°cell is the standard cell potential.

After calculating E°cell and ΔG°, determine the reaction's spontaneity. A negative ΔG° indicates a spontaneous reaction under standard state conditions.

This process demonstrates the relationship between electrode potentials, free-energy change, and reaction spontaneity in electrochemistry.