Question

Three elements \(A, B\) and \(C\) have reduction potentials \(-1.5,-0.05\), and \(+1.50\). Then the correct order of their reducing power is (a) \(A>B>C\) (b) \(B>A>C\) (c) \(C>B>A\) (d) \(B>C>A\)

Short answer

The correct order of reducing power is \(A>B>C\).

Step-by-step solution

Understand Reduction Potentials

Reduction potential is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. The more positive the reduction potential, the more likely the species will gain electrons and undergo reduction.

Compare the Reduction Potentials

Compare the reduction potentials. We have \(A = -1.5\), \(B = -0.05\) and \(C = +1.5\). The greater the reduction potential, the less likely the species is to act as a reducing agent because it prefers to gain electrons itself rather than give them away. Therefore, the reducing power decreases as we move from \(A\) to \(B\) to \(C\).

Identify the Correct Order

Based on the comparison in Step 2, the correct order of reducing power is \(A>B>C\), because species \(A\) with the least reduction potential is the most eager to lose electrons (or reduce other species).

Key concepts

Understanding Electrochemistry

Electrochemistry is a fascinating field that bridges the gap between electricity and chemical reaction. At its core, electrochemistry deals with the flow of electrons from one species to another through chemical reactions. These reactions typically occur in a setup known as an electrochemical cell, where two different metals or conductive materials, called electrodes, are immersed in an electrolyte solution and connected by an external circuit.

The reactions at each electrode involve either the loss of electrons, termed oxidation, or the gain of electrons, called reduction. Oxidation occurs at the anode, while reduction happens at the cathode. The tendency of a material to be oxidized or reduced is indicated by its reduction potential, which is a measured value relative to the standard hydrogen electrode. Understanding this concept helps students to predict the behavior of materials in an electrochemical reaction and is crucial in fields ranging from energy storage in batteries to metallurgy and bioelectrochemistry.

The Concept of Reducing Power

Reducing power refers to the ability of a substance to donate electrons to another species; in other words, its eagerness to be oxidized. In an electrochemical context, the reducing power of a chemical species is inversely related to its reduction potential. This means a substance with a lower (more negative) reduction potential has a higher reducing power because it has a stronger tendency to lose electrons and thereby reduce another substance.

Understanding reducing power is important for predicting the outcome of redox reactions, where the species with greater reducing power will be the one that gets oxidized. This concept is not only academically significant but also possesses vast practical applications, including determining the feasibility of a redox reaction in industrial processes or the discharge sequence of metals in a voltaic cell.

The Role of Chemical Species in Reduction

Chemical species reduction is a half-reaction in which a substance gains electrons, thus reducing its overall charge. The role of a chemical species in a reduction process is quantified by its reduction potential value. For instance, a species with a high positive reduction potential has a greater propensity to acquire electrons compared to one with a more negative value.

In the context of the exercise provided, species with higher positive reduction potential, like C with a value of +1.50, is less likely to act as a reducing agent. Conversely, species with lower or negative reduction potentials, such as A with a value of -1.5, shows a strong tendency to donate electrons, acting as a robust reducing agent. Thus, the correct order of reducing power based on the given reduction potentials would be A (highest reducing power) > B > C (lowest reducing power), analogous to the order of eagerness to lose electrons. This illustration aids students in predicting and rationalizing the flow of electrons in various redox reactions.