Following reaction is involved in present system:
2KMnO4 + 5H2O2 + 3H2SO4 → 2MnSO4 + K2SO4 + 5O2 + 8H2O
From the above balance reaction, it can be seen that 2 moles of KMnO4 is consumed for every 5 moles of H2O2.
Now, percent by mass of hydrogen peroxide in the original solution can be estimated as follows:
percent by mass = [tex] \frac{\text{mass of H2O2(g)}}{\text(volume of H2SO4(ml))}X 100 [/tex]
∴percent by mass = [tex] \frac{\text{1}}{\text(25)}X 100 [/tex]
= 4 %