Re: How can I monitor the rate of a reaction between H2O2 and KMnO4 ?

A different possibility may be to use MnO2 instead.  This compound is a 
catalyst to decompose the H2O2 into H2O and O2.  The reaction may not be as 
fast and would allow you to make some measurements.  The other possibility 
would be to set up several flasks, each with differing concentrations of 
H2O2, using the same amount of the catalyst of your choice, and collect all 
of the O2 produced from each of the flasks at a given time interval.  The 
other possibility is to use 3% H202 and dilute it by 50%.  Try this and 
continue with your dilutions.  Also, you could use about 500ml of the H202 
solution and about 2.00-5.00 grams of the MnO2.  By increasing the amount 
of the H2O2 that needs to "find a spot" on the catalyst, you can 
effectively slow down the reaction.  
As always, you are going to have to spend some time in the lab, trying 
different compositions and combinations.  Please be careful to keep 
accurate notes as to what happens to learn from your experimentation.

Thanks for the question, I hope this helps.

Robert L. Judge