Given at 298 K: E^ _ Fe²⁺/Fe = X Volt; E^ _ Fe³⁺/Fe = Y Volt. The E^ _ Fe³⁺/Fe²⁺ in Volt at 298 K is given by:

Step-by-step solution

The half-reactions and their standard Gibbs free energy changes are given by: Fe²⁺ + 2e⁻ Fe G^ ₁ = -2FX Fe³⁺ + 3e⁻ Fe G^ ₂ = -3FY The required half-reaction is: Fe³⁺ + e⁻ Fe²⁺ G^ ₃ = -1FE^ _ Fe³⁺/Fe²⁺ This reaction is obtained by subtracting the first reaction from the second reaction: G^ ₃ = G^ ₂ - G^ ₁ -FE^ _ Fe³⁺/Fe²⁺ = -3FY - (-2FX) -FE^ _ Fe³⁺/Fe²⁺ = -3FY + 2FX E^ _ Fe³⁺/Fe²⁺ = 3Y - 2X Answer: 3Y-2X