Aluminium is a reactive metal. It reacts readily with dilute acid. However, the metal is protected by a layer of oxide. The chloride ions in the solution can disrupt this layer and let the aluminium reacts with copper(II) ions and hydrogen ions.

2Al(s) + 3CuCl2(aq) → 2AlCl3(aq) + 3Cu(s)

2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)

Hydrogen gas can be ignited and the bluish green colour is due to the presence of copper(II) ions.

Iron reacts with concentrated hydrochloric acid, iron(ll) chloride and hydrogen is formed.

Fe(s) + 2HCl(aq) → FeCl2 (aq) + H2(g)

Iron(II) ions are oxidized by hydrogen peroxide to form Iron(III) ions.

 2FeCl2(aq) + H2O2(aq) +2HCl(aq) → 2FeCl3(aq) +2H2O(l)

Iron(III) ions react with thiocyanate ions to form red complex ions and the iron wire appears "bleeding".

FeCl3(aq) + SCN(aq) → FeSCN2+(aq)