(a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents:

Key Concepts

Reducing Agents

A reducing agent is a substance that donates electrons in a chemical reaction, thereby reducing another substance. The strength of a reducing agent is determined by its ability to lose electrons easily. Elements that are more electropositive, such as alkali metals, typically serve as stronger reducing agents because they readily give up their outermost electrons.

Electrochemical Series

The electrochemical series is a list of elements arranged according to their standard electrode potentials. Elements higher in the series are stronger oxidizing agents, while those lower are stronger reducing agents. Understanding this series helps predict the reactivity of elements in redox reactions, allowing for the arrangement of reducing agents based on their relative strengths.

Redox Reactions

Redox reactions involve the transfer of electrons between two species, where one is oxidized (loses electrons) and the other is reduced (gains electrons). The ability of an element to act as a reducing agent is directly related to its tendency to undergo oxidation. Analyzing the half-reactions involved can clarify the order of reducing agents based on their electron-donating capabilities.