What mass of hydrogen peroxide will be present in 2 litres of a 5 molar solution? Calculate the mass of oxygen which will be liberated by the decomposition of 200 mL of this solution.

Given, V = 2L and Molarity = 5M

We know that Molar mass of H₂O₂ = 34g

Molarity (M) =

=

5 =

W= 340g

Therefore, mass of hydrogen peroxide will be present in 2 litres of a 5 molar solution is 340g.

Mass of oxygen which will be liberated by the decomposition of 200 mL of this solution can be calculated as shown below.

No. of moles =

Molar volume = volume at STP = 22.4 L or 22400ml

No. of moles = = 0.0089

2H₂O₂ → 2H₂O + O₂

From the above equation it is clear that,

2 moles of H₂O₂ → 1 mole of O₂

0.0089 moles of H₂O₂ → moles of O₂

Now, we know mass = no. of moles of O₂ × molecular mass of O₂

= = 0.15g

Mass of oxygen which will be liberated by the decomposition of 200 mL of this solution is 0.15g.