Balance the following reactions using the half reaction method:

Question

a) H₂O₂(aq) + I^-1(aq) <---/---> IO₃^-1(aq) [basic solution]

b) S₂O₃^2-(aq) + Cl₂(l) <---/---> SO₄^2-(aq) + Cl^-1(aq) [acidic solution]

c) Al(s) + MnO₄^-1(aq) <---/---> Al(OH)₄^-1(aq) + MnO₂(s) [basic solution]

Answer 1

You are posting a lot of questions all at once, so I'm going to be selective in which ones I answer. I tend not to do homework for posters, nor do I answer multiple questions from the same poster. So, I've chosen this question to answer for you. And I'll do one in acidic solution and one in basic solution and hopefully you can do the other basic solution.

(b). S₂O₃^2- ==> SO₄^2- ... oxidation half reaction

S₂O₃^2- + 5H2O ==> 2SO₄^2- ... balanced for S and O

S₂O₃^2- + 5H2O ==> 2SO₄^2- + 10H⁺ ... balanced for S, O and H using acid (H⁺)

S₂O₃^2- + 5H2O ==> 2SO₄^2- + 10H⁺ + 8e- ... balanced for mass and charge = balanced oxidation reaction

Cl₂ ==> Cl^- ... reduction half reaction

Cl₂ = 2Cl^- ... balanced for Cl

Cl₂ + 2e- = 2Cl^- ... balanced for mass and charge = balanced reduction reaction

To equalize electrons, multiply reduction reaction by 4 and then add the two reactions together to get...

S₂O₃^2- + 5H2O + 4Cl₂ + 8e- ==> 2SO₄^2- + 10H⁺ + 8e- + 8Cl^-

Finally, combine/cancel like terms to end up with the balanced overall reaction:

S₂O₃^2- + 5H₂O + 4Cl₂ ==> 2SO₄^2- + 10H⁺ + 8Cl^- ... balanced overall reaction

(c). Al ==> Al(OH)₄^- ... oxidation half reaction

Al + 4H2O ==> Al(OH)₄^- ... balanced for Al and O

Al + 4H2O + 4OH- ==> Al(OH)₄^- + 4H2O ... balanced for Al, O and H using base (OH-) and H2O

Al + 4H2O + 4OH- ==> Al(OH)₄^- + 4H2O + 3e- ... balanced for mass and charge = balanced oxid. reaction

MnO₄^- ==> MnO₂ ... reduction half reaction

MnO₄^- ==> MnO₂ + 2H2O ... balanced for Mn and O

MnO₄^- 4H2O ==> MnO₂ + 2H2O + 4OH^- ... balanced for Mn, O and H using base (OH-)

MnO₄^- + 4H2O + 3e- ==> MnO₂ + 2H2O + 4OH^- ... balanced for mass and charge = balanced reduction rx

Since electrons are already equal, simply add the 2 reactions and combine/cancel like terms to get...

Al + 2H₂O + MnO₄^- ==> Al(OH)₄^- + MnO₂ ... balanced overall reaction