Question

Illustrate how copper metal can give different products on reaction with `HNO_(3)`.

Answer 1

On heating with dil. `HNO_(3)`, copper gives copper nitrate and nitric oxide.
`3Cu+8HNO_(3)(dil)overset("Heat")to3Cu(NO_(3))_(2)+4H_(2)O+underset("Nitric oxide")(2NO)`
With conc. `HNO_(3)`, instead of `NO,NO_(2)` is evolved.
`Cu+4HNO_(3)(conc)overset("Heat")toCu(NO_(3))_(2)+2H_(2)O+underset("Nitrogen dioxide")(2NO_(2))`