Spannungsreihe

The Spannungsreihe, also known as the electrochemical series or activity series, is a fundamental concept in chemistry that ranks chemical elements according to their standard electrode potentials. This series helps predict the outcome of redox reactions, particularly those involving metals and their ions in aqueous solutions. Elements are arranged from most reactive to least reactive, or from strongest reducing agent to strongest oxidizing agent.

In the Spannungsreihe, elements that readily lose electrons (metals that are easily oxidized) appear at the top, while elements that readily gain electrons (nonmetals that are easily reduced) appear at the bottom. For instance, alkali metals like sodium and potassium are very high in the series, indicating they are strong reducing agents and will readily react with water or acids. Conversely, noble metals like gold and platinum are at the bottom, signifying they are poor reducing agents and are resistant to oxidation.

The position of an element in the Spannungsreihe dictates whether it can displace another element from its compound. A more reactive element higher in the series can displace a less reactive element lower in the series from its salt solution. For example, zinc, being higher than copper in the series, can displace copper ions from a copper sulfate solution, forming zinc sulfate and solid copper. This principle is crucial in understanding electrochemistry, battery technology, and corrosion processes. The standard electrode potential values, measured in volts, are the quantitative basis for this ranking.