Question

Many metals can be oxidized by the H+ ions in strong acids, such as nitric acid ( HNO3). In these reactions, the H+ ions are reduced to H2 gas. Copper metal (Cu) can also be oxidized by HNO3 but a different reaction occurs. Cu(s)+4H+(aq)+2NO−3(aq)⟶Cu2+(aq)+2NO2(g)+2H2O(l) Determine the oxidation state of each element in HNO3 before the reaction.

Answer 1

Answer: N = +5, O = -2, H = +1

Each H ion has a positive 1 oxidation state when reacting with nonmetals. Each oxygen generally has a -2 (unless in peroxides). The sum of all the states will be 0, so lets set

H + N + O3 = 0

+1 + N - 2(3) = 0

N = +5

so N = +5, O = -2, H = +1