[chrisAP]

hey all. i got a few homework probs i cant figure out, and im stuck. what are the half reactions for the following equations?

Pb(s) + PbO₂(s) + H2SO₄(aq)   PbSO₄(s)

Mn²⁺(aq) + NaBiO₃(s)  Bi³⁺(aq) + MnO4^-(aq)

*I know the complete steps for these in acidic solution, but I don't what to do when you have 3 reactants (first equation), or how to balance the second equation's half-reactions

any help is greatly appreciated!

[Astrokel]

hi, start off with finding which atom is oxidized and which is reduced. in your first case, apparently is Pb. Pb from 0 to +2 as well as from +4 to 0

Pb ---> Pb²⁺
PbO₂ ---> Pb²⁺

same applies to the other case, try it out..

[n0m0r3l0v3_0k]

the 2nd should be
3Mn2+ + 4BiO3- ---> 3MnO4- + 4Bi3+

[Borek]

the 2nd should be
3Mn2+ + 4BiO3- ---> 3MnO4- + 4Bi3+

It is not balanced (hint: charge).