Question

Chem 401 Discussion Workshop #12 Name The following page may or may not be +5 -2 -1 0 6. BrO3 + N2H4 Br + N2 (balance in acid) Page may or may not be required by your instructor. iNzH4:0=2x + 4 X =-2 - Oxid 72 Rxn: 6H+Bv03-> Br-+ 3H2O Red / Rxn: N, Hy -> N2 + 2H2O 7. Cros? + S2042- → Cr(OH)+ S03?- (balance in base) Oxid 12 Rxn: Red 1/2 Rxn:

Answer 1

Ans :

To balance the redox reactions , we start by writing the oxidation and reduction half reactions seperately. Then we balance all elements except hydrogen and oxygen . Oxygen and hydrogen are balanced adding water molecules and hydrogen ions.

The hydrogen ions are balanced adding hydroxide ions.

The half reactions are then added and simplified to get the balanced redox reactions.

so here :

6)

oxid 1/2 Rxn : 3N₂H₄ = 3N₂ + 12H⁺ + 12 e^-

red 1/2 Rxn : 2BrO₃^- + 12H⁺ + 12e^- = 2Br^- + 6H₂O

The balanced equation is given as :

2BrO₃^- + 3N₂H₄ = 2Br^- + 3N₂ + 6H₂O

7)

Oxid 1/2 Rxn : 3S₂O₄^2- + 12OH^- + 6H₂O = 6SO₃^2- + 12H₂O + 6e^-

Red 1/2 Rxn : 2CrO₄^2- + 6e^- + 10H₂O = 2Cr(OH)₃ + 10OH^- + 2H₂O

The balanced equation is given as :

2CrO₄^2- + 3S₂O₄^2- + 2H₂O + 2OH^- = 6SO₃^2- + 2Cr(OH)₃