Consider the following half-reactions: IrCl6^3-+3 e^-⟶Ir+6 Cl^- ℰ^∘=0.77 V PtCl4^2-+2

step 1 Continuing on with electrochemistry, we're essentially looking at how electrons move throughout

Consider the following half-reactions: IrCl6^3-+3...

Consider the following half-reactions: $$\begin{array}{ll}{\mathrm{IrCl}_{6}^{3-}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Ir}+6 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.77 \mathrm{V}} \\ {\mathrm{PtCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt}+4 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.73 \mathrm{V}} \\ {\mathrm{PdCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pd}+4 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.62 \mathrm{V}}\end{array}$$ A hydrochloric acid solution contains platinum, palladium, and iridium as chloro-complex ions. The solution is a constant 1.0$M$ in chloride ion and 0.020$M$ in each complex ion. Is it feasible to separate the three metals from this solution by electrolysis? (Assume that 99$\%$ of a metal must be plated out before another metal begins to plate out.)

Consider the following half-reactions:
$$\begin{array}{ll}{\mathrm{IrCl}_{6}^{3-}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Ir}+6 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.77 \mathrm{V}} \\ {\mathrm{PtCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt}+4 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.73 \mathrm{V}} \\ {\mathrm{PdCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pd}+4 \mathrm{Cl}^{-}} & {\mathscr{E}^{\circ}=0.62 \mathrm{V}}\end{array}$$
A hydrochloric acid solution contains platinum, palladium, and iridium as chloro-complex ions. The solution is a constant 1.0$M$ in chloride ion and 0.020$M$ in each complex ion. Is it feasible to separate the three metals from this solution by electrolysis? (Assume that 99$\%$ of a metal must be plated out before another metal begins to plate out.)

Key Concepts

Electroplating

Electroplating is the process of depositing a metal onto the surface of an electrode by passing electric current through a solution containing the metal ions. Understanding this process involves knowing how electrons reduce metal ions at the cathode to form a solid metal layer.

Selective Electrodeposition

Selective electrodeposition is based on exploiting differences in reduction potentials to deposit one metal preferentially over another. For separation by electrolysis, the potentials should be sufficiently separated so that the deposition of one metal can occur almost exclusively before the next metal starts to deposit.

Standard Reduction Potentials

This concept refers to the intrinsic tendency of different chemical species to be reduced, measured under standard conditions. In electrochemistry, the standard reduction potential indicates how readily a metal ion gains electrons to form the metal, which in turn affects the order in which metals can be deposited during electrolysis.

Nernst Equation

The Nernst equation helps adjust the standard reduction potentials for the actual concentration of the reactants and products in the half-cell reactions. It is essential to determining the actual electrode potential when the system is not under standard conditions, which is crucial in processes involving constant concentrations of certain ions.

Deposition Thresholds and Overpotential

Given criteria such as needing to plate out 99% of a metal before another begins deposition, it is important to consider not just the thermodynamics (reduction potentials) but also the kinetics and overpotentials involved. These factors together determine the feasibility of achieving high purity separation during the electrolysis process.

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