What is the final, balanced equation that is formed by combining these two half reactions?
Cu-Cu2+ + 2e-
NO3 + 2e + 2H* —>N0Z+H20
Cu2+ + NO3 + 4e- + 2H+ -->Cu +
u + NO3 + H20
Cu + NO3
+ 2HCu2+ + NO2 + H20
2Cu + NO3 +
+ 2H+ ->20u2+ +
+ NO 2 + H20
Cu+ NO3 +
+ 2H+
Cu2+ + NO + + 2H20

Cu + 2NO3- + 4H+ > Cu2+ + 2NO2 + 2H20

Explanation:

The half reactions are;Cu > Cu2+ + 2e-

NO3 + 2e + 2H* —> N02 + H20

It is worthy to note that oxidation is the an increase in oxidation number while reduction is a decrease in oxidation number.

In the first half reaction involving Copper, copper has been oxidized as its oxidation number increased from 0 to +2.

IN the reduction half reaction, NO3- has been reduced as its oxidation number decreased from +5 to +4.

In balancing half reactions, the following must be observed;

1. split the reactions into half equations, one for oxidation and the other for reduction.

Cu > Cu2+ + 2e-   ( oxidation)

NO3- + 2e- > NO2   (reduction).

2. balance on half with respect to atoms and charges.

3. balance the other half with respect to atoms and charges

4. balance by adding H+ ions in acidic solution

NO3- + e- > NO2

(-1 )       (-1)             (0)

NO3- + 2H+ +e- > NO2

(-1)       (+2)     (-1)            (0)

5. balance hydrogen by adding water molecules

NO3 - + 2H+ + e - >  NO2 + H2O

6. combine both equations

Cu ---> Cu2+ + 2e-                                  *1

NO3- + 2H+ + e- > NO2 + H2O      *2

= Cu > Cu2+ + 2e-

2NO3- +4H+ + 2e- > 2 NO2 + 2H20

Combined equation  = Cu + 2NO3- + 4H+ > Cu2+ + 2NO2 + 2H20

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.

explanation: no but i do not usually comment