redox equations...help needed

joeywitter · Posted: Sat Mar 05, 2005 8:54 pm Post subject: redox equations...help needed

Hi all.I'm new here and I'm hoping someone could help me with my chem problems.I'm from Croatia so my English isn't really good,but I'm gonna try my best to explain the problems.

1) I was doing an experiment where we were supposed to define the formula of the silver oxide.
The method was this:First I had to make of a solution of AgNO3 and H2O(equation?).Then I had to add a few drops of concentrated NaOH in that solution(equation?).Then,after the sediment was made I had to filter it.After the sediment was dry I heated it with a burner.The formula of the oxide is Ag2O but I'm having troubles with showing the partial redox equations....can anyone help me,PLEASE????
If it's any help,I think that the equations should go like this:
AgNO3(s) + H2O→
the thing that occured in the upper eq + NaOH(conc)→Ag2O(s) +
Ag2O(s) + O2→Ag + O2

2)The other experiment was getting oxygen from KmnO4.The equation goes like this :
KmnO4 →K2MnO4 + MnO2 + O2 but I again need the partial redox equations.

3) I need a partial redox equations for this reaction too : 02 + S8 → SO2

Please help me anyone....

biochem · Junior Member Joined: 08 Mar 2005 Posts: 9

Hey there

Here are some tips that help in figuring out redox equations.

First, you need to work out the half-equations, that is the individual equation for the reaction of each ion present. You should understand the redox reaction itself and know whether an ion is being reduced or oxidized to which ion. That is your starting point. Then just write, say ion/molecule X -----> ion/molecule Y and apply the following steps:

1. Balance all atoms except for oxygen
2. Next, balance oxygen atoms by adding water to the side of the equation deficient in oxygen.
3. Balance hydrogen atoms by adding H+ ions on the side that is deficient in hydrogen.
4. Finally balance charges by adding the appropriate number of electrons to the more positive side of the equation.

Finally you obtain the overall redox equation by multiplying the half-equations by the appropriate number so that the electrons cancel out and then adding the two equations.

Hope this helps and feel free to post your questions if you need more help about this.