the emf of the cell will be maximum for which of the following acids used in the anodic half cell of P=2 atm?

To determine which acid will yield the maximum electromotive force (emf) in the anodic half-cell under a pressure of 2 atm, we need to consider the Nernst equation and the specific reactions occurring at the anode. The emf of a cell is influenced by the concentration of reactants and products, as well as the temperature and pressure conditions.

Understanding the Nernst Equation

The Nernst equation is crucial for calculating the emf of electrochemical cells. It is expressed as:

E = E° - (RT/nF) * ln(Q)

Where:

• E = cell potential (emf)
• E° = standard cell potential
• R = universal gas constant (8.314 J/(mol·K))
• T = temperature in Kelvin
• n = number of moles of electrons transferred
• F = Faraday's constant (96485 C/mol)
• Q = reaction quotient

Factors Influencing emf

The emf will be maximized when the reaction quotient (Q) is minimized. In the context of acids used in the anodic half-cell, the concentration of hydrogen ions (H⁺) plays a significant role. A higher concentration of H⁺ ions will shift the equilibrium towards the products, thus increasing the emf.

Analyzing Different Acids

Common acids that might be considered include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃). Each of these acids dissociates in water to produce H⁺ ions:

• HCl → H⁺ + Cl^-
• H₂SO₄ → 2H⁺ + SO₄^2-
• HNO₃ → H⁺ + NO₃^-

Comparative Analysis

Among these acids, sulfuric acid is a strong acid that completely dissociates in solution, providing a higher concentration of H⁺ ions compared to HCl and HNO₃. For example:

• 1 M HCl yields 1 M H⁺
• 1 M HNO₃ yields 1 M H⁺
• 1 M H₂SO₄ yields 2 M H⁺

Thus, at a pressure of 2 atm, the higher concentration of H⁺ ions from sulfuric acid will lead to a lower value of Q in the Nernst equation, resulting in a higher emf.

Final Thoughts

In summary, when considering the emf of the cell in the anodic half-cell at a pressure of 2 atm, sulfuric acid will provide the maximum emf due to its ability to produce a greater concentration of hydrogen ions. This principle can be applied to other electrochemical systems as well, where the concentration of reactants significantly influences the cell potential.