# Determining conc of H2O2 by titration

by electric.avenue
Tags: conc, determining, h2o2, titration
 P: 8 1. The problem statement, all variables and given/known data I am planning a titration to determine the concentration of commercial 20 volume hydrogen peroxide. I will be titrating it against potassium permanganate. I know that acid, H2SO4, must come into it too, but am unsure as to whether this is added to the H2O2 solution, or the potassium permanganate solution. I have done very little practical work in chemistry, as I attend an evening class, and I need to know: is diluting the 20 volume hydrogen peroxide on a 1: 9 basis with distilled water an adequate dilution? what volume of diluted solution should I make up? what volume of diluted solution for each titration? what conc of potassium permanganate to be used? what conc of H2SO4, and what to add it to? Any help gratefully received. Thanks in adv. 2. Relevant equations 3. The attempt at a solution 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution
 Admin P: 21,727 First things first. To understand what is going on and why you need to know reaction equation. Some information (like titrant concentration and some procedure details) will be probably given by TAs, you won't be able to guess them. Optimal amount of titrant is about 80-90% of burette volume. Then it all boils down to simple stoichiometry. You may check some books on analytical chemistry, this is a standard assay. Borek
 P: 8 Thanks for getting back to me, Borek. Yes, I do have a reaction equation for this: 2 KMnO4 (aq) + 5 H2O2 (aq) + 3H2SO4(aq) ---> 2 MnSO4 (aq) + 5O2 (g) + 8H2O (l) + K2SO4 (aq) No indicator needed because the solution will turn pink when all the H2O2 has reacted. Do I add the H2SO4 to the potassium permanganate solution that goes into the burette, or is it added to a solution of the hydrogen peroxide? I am also very uncertain about what concentrations to use, as different websites recommend different ones, and I have done v little labwork due the the fact that the class I attend is an evening class, and we have very little time. The hydrogen peroxide that we have to determine the concentration of is 20-volume, so would a potassium permanganate solution of 0.05 M be reasonable for this? And to what extent would I need to dilute the commercial hydrogen peroxide? Would 10 ml of commercial 20-volume hydrogen peroxide to 90 ml of distilled water be reasonable?
PF Patron
HW Helper
P: 3,720

## Determining conc of H2O2 by titration

When I plan titrations like this, I assume that I will use about half of the graduated buret volume but you could do as Borek suggests and plan to add between 80% to 90% of the buret volume if you wish. You should be using a 50 mL buret so plan on adding about 25 mL of titrant.