Question

Question #9701f

Answer 1

`"C"_ ((s)) + 4"HNO"_ (3(aq)) -> 2"H"_ 2"O"_ ((l)) + 4"NO"_ (2(aq)) + "CO"_(2(g)) uarr`

Explanation:

You're dealing with a redox reaction in which carbon reduces hot, concentrated nitric acid to nitrogen dioxide, `"NO"_2`, while being oxidized to carbon dioxide, `"CO"_2`, in the process.

The balanced chemical equation that describes this reaction looks like this

`stackrel(color(blue)(0))("C")_ ((s)) + 4"H"stackrel(color(blue)(+5))("N")"O"_ (3(aq)) -> 2"H"_ 2"O"_ ((l)) + 4stackrel(color(blue)(+4))("N")"O"_ (2(aq)) + stackrel(color(blue)(+4))("C")"O"_(2(g))` `uarr`

Here carbon is being oxidized from a `color(blue)(0)` oxidation state in elemental carbon to a `color(blue)(+4)` oxidation state in carbon dioxide.

Nitrogen, on the other hand, is being reduced from a `color(blue)(+5)` oxidation state in nitric acid to a `color(blue)(+4)` oxidation state in nitrogen dioxide.