#volume strength

Volume Strength of \(H_2O_2\) is the volumes of \(O_2\) released on decomposition of one volume of \(H_2O_2\) at STP. so, if a \(H_2O_2\) solution is labelled 10 Vol, decomposing 1L of that solution will give 10L of \(O_2\) and decomposing 1mL of it will give 10mL of \(O_2\).

On heating \(H_2O_2\) decomposes as follows;

Two moles of \(H_2O_2\) on decomposition gives a mole of \(O_2\). Or, in other words, the moles of \(O_2\) formed is half the moles of \(H_2O_2\) decomposed.

If we take 1 mole \(H_2O_2\) solution and decompose it completely it will release 0.5 mole of \(O_2\). At STP one mole of any gas occupies 22.4L. So, 0.5 mole of \(O_2\) will occupy \(22.4 L/mole \times 0.5 mole = 11.2L\).

If the molarity of a \(H_2O_2\) solution is M, 1L of this solution will have M moles of \(H_2O_2\) in it and 1L of it on decomposition will give \(\frac{M}{2}\) moles of \(O_2\). \(\frac{M}{2}\) moles of \(O_2\) will occupy \(22.4 L/mole \times \frac{M}{2} mole = 11.2M L\). This 11.2M L of \(O_2\) has come from 1L of \(H_2O_2\) solution of molarity M.

So, if the molarity of a \(H_2O_2\) solution is M, its volume strength will be 11.2M.