Question

give my answer of ouestion 35

Answer 1

Hello there!!

Silver, when exposed to air, reacts with pollutants like Hydrogen sulphide (H2S), due to which it forms a thin layer of silver sulphide, and turns black. (as Ag2S is black in colour).

Copper, when exposed to air, reacts with Carbon dioxide of the air to form a layer of basic copper carbonate [CuCO3.Cu(OH)2], which is green in colour...

Iron forms hydrated ferric oxide on its surface, [Fe2O3.xH2O] which is called rust, which is a brown powdery substance...

Hope this helps!
Thanks..

Answer 2

1.Reaction of COPPER - Cu + O2 + H2O + CO2 --------- CuCO3.Cu(OH)2 [GREEN] (Basic copper carbonate )
2. Reaction of IRON - 2Fe 3/2O2 + xH2O ------- Fe2O3.xH2O [BROWN] ( Rust )
3. SILVER - Ag + H2S --------- Ag2S + H2 [BLACK] (Silver sulphide )
The colours obtained on the metals is due to the deposition of metal carbonates/rust/sulphides on the surface due to their reaction with other molecules present in the atmosphere.