Finding Standard Gibbs Free energy for half cell reaction.

In summary: K) + 17.607x10^-9(298K)^2)V/F = -5.757 kJ/molThe standard Gibbs free energy of the silver|silver chloride half cell reaction at 298 K can be calculated as follows:G = -1*96,485C/mol*(-0.00558 + 2.6967x10^-3(298K) - 8.2299x10^-6(298K)^2 + 5.869x10^-9(298K)^3)G = -8.541 kJ/molThe standard enthalpy of the silver|silver chloride half cell reaction at 298
  • #1
jtruth914
21
0
The standard potential of the Cl−(aq.)|AgCl(s)|Ag(s) electrode in the vicinity of T = 298 K has been found to fit the expression

E[itex]\theta[/itex]/V = -0.00558 + 2.6967x10^-3(T/K) - 8.2299x10^-6(T/K)^2 + 5.869x10^-9(T/K)^3

Find the standard Gibbs free energy, the standard enthalpy, and the standard entropy of the silver|silver chloride half cell reaction at 298 K.

My question is do I take the derivative of this equation to find entropy? I'm confused because it states it's a half cell, and I know that the equation (dEcell/dT)= DS/vF pertains to the complete reaction not the half cell.
 
Last edited:
Physics news on Phys.org
  • #2
The standard Gibbs free energy of the silver|silver chloride half cell reaction at 298 K can be calculated using the following equation:G = -nFE = -zF(E/V)where n is the number of moles of electrons transferred in the reaction, z is the valence of the species being oxidized or reduced, F is Faraday's Constant (96,485 C/mol), and E/V is the standard potential of the electrode.For the silver|silver chloride half cell reaction, n=1, z=1, and E/V = -0.00558 + 2.6967x10^-3(T/K) - 8.2299x10^-6(T/K)^2 + 5.869x10^-9(T/K)^3. Thus, the standard Gibbs free energy at 298 K is:G = -1*96,485C/mol*(-0.00558 + 2.6967x10^-3(298K) - 8.2299x10^-6(298K)^2 + 5.869x10^-9(298K)^3)G = -8.541 kJ/molThe standard enthalpy of the silver|silver chloride half cell reaction at 298 K can be calculated as follows:H = G + T*Swhere S is the standard entropy of the reaction. The standard entropy of the silver|silver chloride half cell reaction at 298 K can be calculated using the following equation:S = -(dE/dT)V/Fwhere dE/dT is the derivative of the standard potential with respect to temperature, V is the volume of the cell, and F is Faraday's Constant.For the silver|silver chloride half cell reaction, dE/dT = 2.6967x10^-3 - 16.4598x10^-6(T/K) + 17.607x10^-9(T/K)^2, V = 1 L, and F = 96,485 C/mol. Thus, the standard entropy at 298 K is:S = -(2.6967x10^-3 - 16.4598x
 

1. What is the purpose of finding the standard Gibbs free energy for a half cell reaction?

The standard Gibbs free energy is a measure of the energy available to do work in a chemical reaction. For a half cell reaction, it indicates the potential of the cell to produce electrical energy. By finding the standard Gibbs free energy, we can determine the feasibility of a reaction and predict the direction it will proceed.

2. How is the standard Gibbs free energy calculated for a half cell reaction?

The standard Gibbs free energy for a half cell reaction can be calculated using the Nernst equation, which takes into account the standard electrode potential and the concentrations of the reactants and products. This equation is given by ΔG° = -nFE°, where n is the number of electrons transferred, F is the Faraday constant, and E° is the standard electrode potential.

3. What are the units for standard Gibbs free energy?

The units for standard Gibbs free energy are joules per mole (J/mol) in the SI system. However, it is also commonly expressed in kilojoules per mole (kJ/mol) or calories per mole (cal/mol).

4. Can the standard Gibbs free energy be negative?

Yes, the standard Gibbs free energy can be negative. A negative value indicates that the reaction is thermodynamically favorable and will proceed spontaneously in the forward direction. A positive value, on the other hand, indicates that the reaction is not spontaneous and will require an input of energy to proceed.

5. How is the standard Gibbs free energy related to the equilibrium constant?

The standard Gibbs free energy is related to the equilibrium constant (K) through the equation ΔG° = -RTlnK, where R is the gas constant and T is the temperature in Kelvin. This equation shows that the standard Gibbs free energy and the equilibrium constant are inversely proportional, meaning that a larger equilibrium constant (indicating a greater amount of products compared to reactants) will result in a more negative standard Gibbs free energy.

Similar threads

  • Biology and Chemistry Homework Help
Replies
7
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
9
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Advanced Physics Homework Help
Replies
1
Views
662
  • Biology and Chemistry Homework Help
Replies
6
Views
2K
  • Biology and Chemistry Homework Help
Replies
4
Views
3K
  • Biology and Chemistry Homework Help
Replies
4
Views
4K
Replies
8
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
6K
Back
Top