Why concentrated sulphuric acids can't react with metals?
Answers
Answer:
Sulfuric acid -when concentrated- reacts with metals as an oxidising agent.
For example, with copper it undergoes a redox reaction:
Cu+2H2SO4−>CuSO4+SO2+2H2O
The copper is oxidised to copper (II) ions.
Cu−>Cu2++2e−
The sulfuric (VI) acid is reduced to sulfur (IV) dioxide and water (the sulfate (VI) ions that formed the copper sulfate are not reduced).
This reduction can be simplified, as this is pretty complicated to explain in words:
2H+H2SO4+2e−−>SO2+2H2O
The 2 H+ ions came from the other sulfuric acid molecule, the one that didn’t get reduced. The 2 electrons came from the copper being oxidised.
H2SO4−>2H++SO2−4
This leaves over the copper (II) ion and sulfate (VI) ion, which form copper (II) sulfate.
Cu2++SO2−4−>CuSO4
Explanation: