what are the half reactions for
a) Cr(NO3)2
b) Pb(NO3)2
I know that Cr and Pb are:
Cr^2+ +2e- -> Cr
Pb^2+ +2e- -> Pb
I just don't know how to do the half reaction for (NO3)2
I believe NO3^- is just a spectator ion.
To determine the half reactions for (NO3)2 in the compounds Cr(NO3)2 and Pb(NO3)2, you need to consider the reduction of the nitrate ion (NO3-). Nitrate ion can be reduced to various products depending on the reaction conditions.
In this case, let's assume the reduction of nitrate ion to nitrogen dioxide (NO2), which is a common reaction when nitrate salts are subjected to strong reducing agents.
The half-reaction for the reduction of (NO3)2 to NO2 can be written as follows:
NO3- + 2H+ + 2e- -> NO2 + H2O
Note that the reaction requires two hydrogen ions (H+) and two electrons (2e-) as reactants to balance the charges.
Therefore, the half reactions for Cr(NO3)2 and Pb(NO3)2 can be written as:
a) Cr(NO3)2:
Cr^2+ + 2e- -> Cr (reduction half-reaction)
NO3- + 2H+ + 2e- -> NO2 + H2O (oxidation half-reaction)
b) Pb(NO3)2:
Pb^2+ + 2e- -> Pb (reduction half-reaction)
2NO3- + 4H+ + 4e- -> 2NO2 + 2H2O (oxidation half-reaction)
Remember that these are just examples, and depending on the reaction conditions, different products may form when nitrate ion is reduced.