Question

How can volume strength be calculated?

Answer 1

Volume strength: Volume strength is the volume of oxygen at STP liberated from one volume sample of hydrogen peroxide on heating.

The term “volume strength” is only used for hydrogen peroxide.

$\mathrm{Volume}\mathrm{strength}=\frac{\mathrm{Volume}\mathrm{of}\mathrm{oxygen}}{\mathrm{Volume}\mathrm{of}\mathrm{hydrogen}\mathrm{peroxide}\mathrm{used}}$

If we look for an example-

Step 1: Calculating strength

Volume strength of Hydrogen peroxide can be defined as the term which is used to express the concentration of ${\mathrm{H}}_2{\mathrm{O}}_2$ with respect to the volumes of oxygen gas based on its decomposition to form water and oxygen.

For example, Let us assume a Hydrogen peroxide solution of $1.5\mathrm{N}$.

$1.5\mathrm{N}=1.5\mathrm{g}$ equivalent weight in 1 L solution.

The equivalent weight of ${\mathrm{H}}_2{\mathrm{O}}_2$is $17\mathrm{g}$.

We know that,

$$\begin{gathered} \mathrm{Strenght}\mathrm{of}{\mathrm{H}}_2{\mathrm{O}}_2=\mathrm{Normality}\times \mathrm{Equivalent}\mathrm{weight} \\ \Rightarrow \mathrm{Strenght}\mathrm{of}{\mathrm{H}}_2{\mathrm{O}}_2=1.5\times 17\mathrm{g}=25.5 \end{gathered}$$

Step 2: Calculating volume strength

We have, $2{\mathrm{H}}_2{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$

From the above reaction, we can see that 2 moles of ${\mathrm{H}}_2{\mathrm{O}}_2$ produces 1 mole of Oxygen

$\therefore$2 mole of ${\mathrm{H}}_2{\mathrm{O}}_2$ weighs $2\left(2\times 1+16\times 2\right)=34\times 2=68\mathrm{g}$

68g of ${\mathrm{H}}_2{\mathrm{O}}_2$ produces 22.4L of oxygen

$\therefore$25.5 g of ${\mathrm{H}}_2{\mathrm{O}}_2$ will produce$\frac{22.4}{68}\times 25.5=8.4\mathrm{L}$

Thus in this manner, we can calculate the volume strength of ${\mathrm{H}}_2{\mathrm{O}}_2$.