Summary

Videos

References

Daniel cell: As Daniel cell starts functioning, the concentration of copper (ii) ions starts decreasing and that of zinc ions starts increasing.

Thus Q, the reaction quotient in the Nernst equation is increasing, shows that the cell voltage will decrease. At one stage, the concentrations of both the ions become equal. This indicates that the reaction will reach equilibrium and the voltmeter will read zero.

The Nernst equation can be written as,

At, equilibrium K_{c} = [Zn^{2+}]/[Cu^{2+}]

EÂ°_{cell} = 2.303RT/nF ln K_{c}

at T = 298 K

ln K_{c} = (EÂ°_{cell}V)n/0.059V

**Relation between Gibbs free energy and cell potential:**

âˆ†G^{0} = -nFE_{cell}

âˆ†G^{0} = Gibbs free energy at standard conditions

E^{0}cell = Cell potential at standard conditions

n = number of electrons transferred in a reaction

E^{0}cell is an intensive property

âˆ†G^{0} is an extensive property

âˆ†G = -RT lnK

âˆ†G^{0} = Gibbs free energy

R = Ideal gas constant

K = Equilibrium constant

âˆ†G^{0} = -nFE_{cell}

âˆ†G |

For galvanic cell, the cell potential is always positive thus Gibbs free energy for a galvanic cell is negative, which is consistent with a spontaneous process.

Daniel cell: As Daniel cell starts functioning, the concentration of copper (ii) ions starts decreasing and that of zinc ions starts increasing.

Thus Q, the reaction quotient in the Nernst equation is increasing, shows that the cell voltage will decrease. At one stage, the concentrations of both the ions become equal. This indicates that the reaction will reach equilibrium and the voltmeter will read zero.

The Nernst equation can be written as,

At, equilibrium K_{c} = [Zn^{2+}]/[Cu^{2+}]

EÂ°_{cell} = 2.303RT/nF ln K_{c}

at T = 298 K

ln K_{c} = (EÂ°_{cell}V)n/0.059V

**Relation between Gibbs free energy and cell potential:**

âˆ†G^{0} = -nFE_{cell}

âˆ†G^{0} = Gibbs free energy at standard conditions

E^{0}cell = Cell potential at standard conditions

n = number of electrons transferred in a reaction

E^{0}cell is an intensive property

âˆ†G^{0} is an extensive property

âˆ†G = -RT lnK

âˆ†G^{0} = Gibbs free energy

R = Ideal gas constant

K = Equilibrium constant

âˆ†G^{0} = -nFE_{cell}

âˆ†G |

For galvanic cell, the cell potential is always positive thus Gibbs free energy for a galvanic cell is negative, which is consistent with a spontaneous process.