Titration problem - need help urgently?

Question

I am trying to titrate acidified Hydrogen Peroxide (28ml Hydrogen Peroxide in 1liter of 0.5 mol Sulphuric acid) with 0.02mol Pot. Permagnate and the reading was 4.0 ml. However the reading range given in the instruction it should be between 23.0 and 25.0 ml. How to solve the problem ? I tried diluting the KMnO4 but no much diff.

I'm not looking for criticism just answers. If you're someone who can really help me deeply appreciated if not don't bother. Thanks for those who are doing so.

Answer 1

Wow let's see. M1V1=M2V2
0.02x4=Zx24
Z=0.0033Molar
So you need a 0.0033M for the K.P. Try that (I have worked with this standard actually a 0.0025M concentration), or use a more diluted sulphuric acid. Tell me how it goes it would be nice to find out.

Answer 2

First of all you have a redox reaction with more than one e so the formula given in the previous answer applies to normality and not to molarity. In general N=aM where a is the number of H+/OH- per acid/base molecule or number of e for a redox reaction.

In acid solution Mn of KMnO4 goes from +7 to +2 so a=5.
For H2O2 you have O going from -1 to 0 so a=1.

Thus for titration you have

a1M1V1=a2M2V2=> 1*M1*V1=5*M2*V2.

You are not giving us all the proper numbers so I can't know for sure what's wrong.From the looks of it you prepared 0.02M KMnO4 instead of 0.02N and thus you have 5-times more oxidating equivalents and you need 5-times less volume to titrate.

Otherwise, if you dilute 5 times the KMnO4 solution and still you get the same volume, something's wrong with your reagents/procedure.

Answer 3

You check the strength of the burette solution against standard solutions. If your burette solution is not of 0.02 M KMnO4, then you adjust the strength accordingly before performing your titration.

Answer 4

C'mon, I have to do this stuff at work every day. Do your own God damned homework...