Name of the experiment: Determination of the conc. of Hydrogen Peroxide
(H2O2) by redox titration.
Reagents:
a) Potassium Permanganet 0.02M KMnO4:
We know, W=SMV ; where S=Conc. in molarity, M=Molecular weight
of KMnO4 (158.03g/L), V=Volume in Liter (take 200ml i.e. 0.2L). So,
Weight of KMnO4 need= 0.02*158.03*0.2 =0.63212g. Hence we have to
weight 0.63212g KMnO4 and dissolve it in 200ml of distilled water to
prepare 0.02M KMnO4 solution. This solution is taken into burette to do
titration and the volume consumed recorded carefully.
b) Hydrogen Peroxide(H2O2) of unknown concentration:
Take 02ml 0f H2O2 and dilute it with 100ml distilled water and to it add
1N H2SO4. Finally titrate the unknown conc. of H2O2 with 0.02M KMnO4
solution with constant shaking and little heating until the color changes.
Reaction & Calculation:
5H2O2 + 2KMnO4 + 3H2SO4 → 5O2 + 2MnSO4+ K2SO4+ 8H2O
e1S1V1=e2S2V2
; where, S1= Concentration of H2O2 to be determined, S2= Conc. of KMnO4
,V1= Volume of H2O2 , V2= Volume consumed in burette,
e1 & e2 = number of how many molecules reacting in the reaction.
So, S1 = (e2S2V2)/(e1V1)
The calculated result multiplied by 100 to get result in %.
Precaution:
1. Rinse pipette with distilled water each time before and after taking H2O2
and H2SO4 .
2. Always add H2SO4 dropwise into water, not directly add water into conc
H2SO4 to avoid fumes or even fire hazard.
3. Don’t spill a single drop of conc H2O2 or H2SO4 on floor or anywhere
because H2SO4 is a dehydrating agent can burn most substances within a
minute.
4. When to discharge H2SO4 or H2O2 please make them diluted with
enough water. If H2SO4 spilling occur then firstly neutralize it by adding
caustic soda solution on it.