A solution contains the ions H^+, Ag^+, Pb^2+, and Ba^2+, each at a concentration of 1.0 M. (a)

step 1 In answering this question, we have to look into the reduction cell electrode potentials for the

A solution contains the ions H^+, Ag^+, Pb^2+, and Ba^2+,...

A solution contains the ions $\mathrm{H}^{+}, \mathrm{Ag}^{+}, \mathrm{Pb}^{2+},$ and $\mathrm{Ba}^{2+},$ each at a concentration of $1.0 \mathrm{M}$. (a) Which of these ions would be reduced first at the cathode during an electrolysis? (b) After the first ion has been completely removed by electrolysis, which is the second ion to be reduced? (c) Which, if any, of these ions cannot be reduced by the electrolysis of the aqueous solution?

A solution contains the ions $\mathrm{H}^{+}, \mathrm{Ag}^{+}, \mathrm{Pb}^{2+},$ and $\mathrm{Ba}^{2+},$
each at a concentration of $1.0 \mathrm{M}$.
(a) Which of these ions would be reduced first at the cathode during an electrolysis?
(b) After the first ion has been completely removed by electrolysis, which is the second ion to be reduced?
(c) Which, if any, of these ions cannot be reduced by the electrolysis of the aqueous solution?

Key Concepts

Standard Reduction Potential

This concept refers to the voltage associated with the tendency of a species to gain electrons under standard conditions. A higher (more positive) reduction potential means that the species is more likely to be reduced, which helps predict the order in which different ions will be reduced during electrolysis.

Cathodic Reactions

Cathodic reactions occur at the negative electrode (cathode) during electrolysis, where electrons are supplied to species in the solution, causing them to be reduced. Understanding these reactions is crucial for determining which species will deposit first based on their intrinsic reduction potentials.

Electrolysis in Aqueous Solutions

This is the process by which electrical energy is used to drive chemical reactions in a water-based solution. The presence of water means that, aside from the ions of interest, water can also undergo reduction, which can compete with the reduction of metal ions, thereby affecting the overall outcome of the electrolysis.

Competition between Ion Reduction and Water Reduction

In an aqueous medium, water reduction (leading to hydrogen evolution) can compete with the reduction of dissolved metal ions. This competition is significant because if an ion has a more negative reduction potential than water, water will be reduced preferentially. Thus, only ions with sufficiently positive reduction potentials will be reduced and deposited at the cathode.

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