Question

I need to determine the concentration of hydrogen peroxide in a solution using titrimetric analysis

25 cm3 of the hydrogen peroxide solution was used

the concentration of sodium thiosulphate is 0.1046M (used in the burette)

the overall volume used was 26.4 cm3

Answer 1

Balanced reaction is

2 Na₂S₂O₃ + 4 H₂O₂ Na₂S₂O₃ + Na₂SO₄ + 4H₂O.

Mole ratio of sodium thiosulphate and hydrogen peroxide

= 2:4

= 1:2.

Now, milimoles of sodium thiosulphate present in the solution

= molarity × volume

= 0.1046 × 26.4

= 2.76

Again,

milimoles of hydrogen peroxide = 2× milimoles of sodium thiosulphate

= 2× 2.76

= 5.52 .

Now, molar concentration of hydrogen peroxide solution

= ( milimoles of hydrogen peroxide/volume of hydrogen peroxide solution)

= (5.52 milimoles /25 cm³)

= 0.2209 M.

( Molarity = moles/L = milimoles/cm³)