Question

1.00L of a hydrogen peroxide solution produces 25L of oxygen gas at 0°C and 1 atm.
a) Calculate the concentration of this solution in units of molarity.
b) Calculate the concentration of this solution in units of (m/v) percent.

Answer 1

Ans :

a)

volume of oxygen = 25 L

temperature = 0 C = 273.15 K

pressure = 1 atm

using ideal gas law , pV = nRT

R = 0.0821 L.atm/mol.K

putting values :

1 x 25 = n x 0.0821 x 273.15

n = 1.115 mol

The reaction is given as :

2H2O2 = 2H2O + O2

So 2 mol H2O2 gives one mol oxygen gas

Then the number of mol of hydrogen peroxide here will be : 2 x 1.115 mol = 2.23 mol

Molarity = mol solute / volume of solution in L

= 2.23 mol / 1.00 L

= 2.23 M

b)

mass of hydrogen peroxide = mol x molar mass

= 2.23 mol x 34.0147 g/mol

= 75.8 g

volume of solution = 1.00 L = 1000 mL

m/v % = ( mass of solute / volume of solution ) x 100

= ( 75.8 / 1000) x 100

= 7.58 %