Question 19 write a balanced half-reaction for the oxidation of gaseous nitrogen dioxide to nitrate ion in acidic aqueous solution. be sure to add physical state symbols where appropriate.

This will be the balanced half reaction:

NO₂(g)  + H₂O (l) →  NO₃⁻(aq)  + 1 e⁻  + 2H⁺ (aq)

Explanation:

In acidic medium, the redox balance has to be done as this way.

As it is an oxidation, we know that oxidation state has increased.

NO₂(g)   →  NO₃⁻(aq)  + 1 e⁻

Nitrogen in NO₂ acts with +4; in the nitrate, N acts with +5

The nitrogen has released 1 electron.

As we are in acidic medium, we must complete with water, in the same side, as we have less oxygens and in the opposite side, with protons to balance the H. This will be the balanced half reaction:

NO₂(g)  + H₂O (l) →  NO₃⁻(aq)  + 1 e⁻  + 2H⁺ (aq)

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.