A more reactive metal has a greater tendency to lose electrons than a less reactive metal. In an appropriate aqueous system, it can reduce ions of a less reactive metal, depositing that metal while forming its own ions. Use the supplied activity order rather than guessing from position alone. If zinc is above copper, Zn+Cu2+→Zn2++ Cu is favoured in the simple activity-series model.
Metals above hydrogen commonly react with dilute non-oxidising acids to release H2, although oxide coatings can slow reactions. A more reactive sacrificial metal can protect iron by being oxidised instead. A barrier coating instead separates the metal from water or oxygen. Metal extraction and corrosion involve electron transfer, but observed speed also depends on conditions and protective layers.
Example 1
Given Mg>Zn>Fe>H> Cu, does Fe displace Cu2+?
Yes. Fe is above Cu and can lose electrons as Cu2+ gains them: Fe+Cu2+→Fe2++ Cu.
Example 2
Balance magnesium with dilute hydrochloric acid.
Mg+2HCl → MgCl2+H2. Magnesium loses two electrons and two H+ gain them to form H2.
Watch out:In this model it displaces ions of metals below it in the supplied activity series.
Metal activity and displacement practice | Year 11 Chemistry | Ascent Arcade