# Homework Help: Total # of electrons transferred

1. Oct 26, 2005

### m0286

Hello...
Im working on a chemistry assignment for first year chem (university). The question says:
What is the TOTAl number of electrons transferred when yje following equationis balanced (for acid media) with integer coefficients? Br2(l) + ClO3-(aq) + H2O(l) --> BrO3-(aq)+ Cl-(aq) + H+(aq)
Sorry i woulda used the special writing thing buit i forget how to. I know i shoulda got help sooner and its due at 6am. so any help asap is appreciated.

2. Oct 26, 2005

### Cesium

Br2(l) + ClO3-(aq) + H2O(l) --> BrO3-(aq)+ Cl-(aq) + H+(aq)
1. Write the half reactions.
ClO3- --> Cl-
Br2 --> BrO3-
2. Balance the atoms, leaving H and O for last.
ClO3- --> Cl- + 3H2O
Br2 + 6H2O --> 2BrO3-
3. Balance H with hydrogen ions:
6H+ + ClO3- --> Cl- + 3H2O
Br2 + 6H2O --> 2BrO3- + 12H+
4. Balance charge with electrons:
6e- + 6H+ + ClO3- --> Cl- + 3H2O
Br2 + 6H2O --> 2BrO3- + 12H+ + 10e-
5. Add up equations (need to multiply to balance electrons):
10[6e- + 6H+ + ClO3- --> Cl- + 3H2O] =
6[Br2 + 6H2O --> 2BrO3- + 12H+ + 10e-] =

60e- + 60H+ + 10ClO3- --> 10Cl- + 30H2O
6Br2 + 36H2O --> 12BrO3- + 72H+ + 60e-
-----------------------------------------
6Br2 + 10ClO3- + 6H2O --> 12BrO3- + 10Cl- + 12H+

Add up the electrons exchanged in the reaciton and there's your answer (the last step of adding the equation wasn't really necessary to solve your problem). Hope you understand what I did.

3. Oct 27, 2005

### Staff: Mentor

Cesium: your final equation should be divided by 2 :)

This equation can be balanced without redox approach.