Question

The volume strength of 3% w/v H₂O₂?

Answer 1

% w/v means "weight per volume", i.e. 3g H2O2 per 100mL (of whatever solvent).

Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of >68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous, and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers.

The SI unit of w/v is kg/m3

for example – if the volume strength is 20 volume , it means that 1 cm3 of h2o2 will produce from 20 cm3 of oxygen gas .
acc to the equation
2 moles of h2o2 = 22.4 L of oxygen at STP .
so, by that first of all u have to calculate the MOLARITY of the solution .
and use the formula
moles of solute / volume of solution
and the volume of solution is given as 11.2
and u ned to calculate the no of moles .
and use the formula
mass/ molar mass , or given mass / molar mass
and findout the no of moles ,
THE STRENGTH CAN BE CALCULATED BY THE FOLLOWING FORMULA
11.2 * MOLARITY OF THE SOLUTION .
from the prev formula , u find molaritty and apply it here , u will get the strength