Question

A student has been collecting silver and copper coins. One day he observed that a black coating on silver coins and green coating on copper coins. Give the chemical names of the black and green coating. How are they formed?

Answer 1

Black coating on silver coins is due to silver sulphide(Ag2s).

2 Ag(s) + H2S(g) -----  Ag2S(s)  + H2(g).
 
Green Coating on copper coins is due to copper carbonate and copper hydroxide.

2 Cu + H2O + CO2 + O2  ------ >  Cu(OH)2 + CuCO3


Hope this helps.

Answer 2

Hi

Here goes the answer