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AgCl + e- ----------- Ag(s) + Cl-

E0 = 0.22v

Ag+ + e- ---------- Ag

E0 = 0.80v

the Ksp of AgCl under standard conditions of temp. will be

plz explain in detail

amit singhal , 15 Years ago
Grade 12
anser 1 Answers
Askiitians Tutor Team

To determine the solubility product constant (Ksp) of silver chloride (AgCl) under standard conditions, we need to analyze the given half-reactions and their standard electrode potentials (E0). The Ksp can be derived from the relationship between the solubility of the salt and the equilibrium concentrations of its ions in solution.

Understanding the Half-Reactions

We have two half-reactions provided:

  • AgCl + e- → Ag(s) + Cl- (E0 = 0.22 V)
  • Ag+ + e- → Ag(s) (E0 = 0.80 V)

The first half-reaction shows the reduction of AgCl to solid silver and chloride ions, while the second half-reaction represents the reduction of silver ions to solid silver. The standard electrode potential indicates the tendency of a species to gain electrons; a higher value means a stronger tendency to be reduced.

Calculating the Ksp

To find the Ksp of AgCl, we need to establish the equilibrium expression for its dissolution:

AgCl(s) ⇌ Ag+(aq) + Cl-(aq)

The Ksp expression is given by:

Ksp = [Ag+][Cl-]

Finding the Standard Cell Potential

Next, we can find the overall cell potential (Ecell) for the dissolution of AgCl by combining the two half-reactions. The overall reaction can be represented as:

AgCl(s) ⇌ Ag+(aq) + Cl-(aq)

To find Ecell, we subtract the reduction potential of the half-reaction that produces Ag+ from the reduction potential of the half-reaction that produces Ag(s):

Ecell = Ecathode - Eanode

Here, the cathode is the reduction of Ag+ to Ag(s) (0.80 V), and the anode is the reduction of AgCl to Ag(s) and Cl- (0.22 V):

Ecell = 0.80 V - 0.22 V = 0.58 V

Relating Ecell to Ksp

The relationship between the cell potential and the solubility product can be expressed using the Nernst equation. At standard conditions, the equation simplifies to:

Ecell = (RT/nF) * ln(Ksp)

Where:

  • R = universal gas constant (8.314 J/(mol·K))
  • T = temperature in Kelvin (standard is 298 K)
  • n = number of moles of electrons transferred (1 for AgCl)
  • F = Faraday's constant (96485 C/mol)

Substituting the values into the equation gives:

0.58 V = (8.314 J/(mol·K) * 298 K / (1 * 96485 C/mol)) * ln(Ksp)

Calculating the left side:

0.58 V = (0.025693 V) * ln(Ksp)

Now, we can isolate ln(Ksp):

ln(Ksp) = 0.58 V / 0.025693 V ≈ 22.6

Exponentiating both sides gives:

Ksp = e22.6 ≈ 5.0 x 109

Final Thoughts

The solubility product constant (Ksp) of silver chloride under standard conditions is approximately 5.0 x 109. This high value indicates that AgCl is relatively insoluble in water, which is consistent with its known properties. Understanding the relationship between electrochemical potentials and solubility products is crucial in fields like analytical chemistry and materials science.

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