The most reactive metals, such as sodium, will react with cold water to produce hydrogen and the metal hydroxide:
2Na + 2H2O => 2NaOH + H2
Metals in the middle of the reactivity series, such as iron, will react with acids such as sulfuric acid (but not water at normal temperatures) to give hydrogen and a metal salt, such as iron(II) sulfate:
Fe + H2SO4 => FeSO4 + H2
An iron nail in a copper sulphate solution can soon change colour as metallic copper is coated with the iron(II) sulphate.
Fe + CuSO4 => Cu + FeSO4
Generally, any of the metals that are lesser in the reactivity series can be replaced by metal: higher metals reduce lower metal ions. This is used for the thermite reaction for the production of small amounts of metallic iron and for the preparation of titanium by kroll process (Ti is approximately the same level as Al in the reactivity series). For instance, iron(III) oxide is decreased into iron and aluminium oxide is converted in this process.
2Al + Fe2O3 -> 2Fe + Al2O3
Likewise, the removal of titanium from tetrachloride can be achieved using magnesium, which in the end forms magnesium chloride:
2Mg + TiCl4 => Ti + 2MgCl2
Other factors may, however, come into play as metal potassium can be prepared by reducing sodium potassium chloride to 850 ° C. Although sodium in the reactivity series is less than potassium, the reaction can continue since potassium is volatile and the mixture is distilled.
Na + KCl => K + NaCl