Chemical reaction in which a less reactive element is replaced in a compound by a more reactive one.
For example, the addition of powdered zinc to a solution of copper(II) sulphate displaces copper metal, which can be detected by its characteristic colour:
Zn(s) + CuSO4(aq) ® ZnSO4(aq) + Cu(s)
The copper is taken out of the solution and is deposited as a solid (s).
The ‘Sun of May’ was added in 1818. The blue bands are a shade known as ‘celeste’, said to be the colour of the sky which inspired Argentine revolutionary Manuel Belgrano before battle. Effective date: 16 August 1985.