Hydrogen Peroxide Preparation Structure Reactions - UNSOLVED PRACTICE SET

Q7. Draw the structure of hydrogen peroxide showing the O–O bond and the dihedral angle. Why is it called a "non-planar" molecule?

Q8. Write the chemical equation for the preparation of hydrogen peroxide from barium peroxide (BaO₂) and phosphoric acid (H₃PO₄). Why is H₃PO₄ preferred over H₂SO₄?

Q9. Hydrogen peroxide acts as an oxidising agent in acidic medium. Show this by writing the reaction of H₂O₂ with ferrous sulphate (FeSO₄) in acidic medium.

Q10. Hydrogen peroxide can also act as a reducing agent. Write the reaction of H₂O₂ with acidified potassium permanganate (KMnO₄) to justify this.

Q11. Your mother uses a 3% hydrogen peroxide solution to disinfect a minor cut on your finger. Why is a dilute solution used instead of concentrated H₂O₂? What happens if concentrated H₂O₂ comes in contact with skin?

Q12. Why is hydrogen peroxide stored in dark-coloured bottles with stabilisers like urea or phosphoric acid? What happens if it is exposed to light or heat?

Q13. Describe the structure of hydrogen peroxide molecule:

(a) Draw the open-book structure showing bond angles

(b) Explain the O–O bond and O–H bonds

(c) Discuss why the molecule is non-planar

(d) Explain the significance of the dihedral angle in the solid and gaseous phases

Q14. Discuss the preparation of hydrogen peroxide by:

(a) Laboratory method (from barium peroxide)

(b) Industrial method (2-ethylanthraquinone process)

(c) Electrolysis of sulphuric acid

Compare these methods in terms of purity, cost, and scale of production.

Q15. Hydrogen peroxide is used extensively in India — from bleaching cotton textiles in Surat to treating wastewater in Delhi. Discuss:

(a) Its role as an eco-friendly bleaching agent compared to chlorine

(b) Its use in environmental applications (wastewater treatment)

(c) Its use in the pharmaceutical and cosmetic industries

(d) One safety precaution that must be followed while handling H₂O₂

Q16. A 30% hydrogen peroxide solution (by mass) is commonly called "100 volume" hydrogen peroxide because 1 mL of it liberates 100 mL of oxygen at STP.

(a) Calculate the mass of H₂O₂ in 100 g of 30% solution.

(b) Using the decomposition reaction 2H₂O₂ → 2H₂O + O₂, calculate the volume of O₂ liberated at STP from 34 g of pure H₂O₂.

(c) Verify if 1 mL of 30% H₂O₂ (density ≈ 1.11 g/mL) actually produces approximately 100 mL of O₂ at STP.

[Given: Molar mass of H₂O₂ = 34 g/mol, Molar volume at STP = 22.4 L]

Q17. In a redox titration, 20 mL of H₂O₂ solution reacts completely with 25 mL of 0.02 M KMnO₄ solution in acidic medium.

(a) Write the balanced redox equation for the reaction.

(b) Calculate the molarity of the H₂O₂ solution.

(c) Calculate the volume strength of the H₂O₂ solution.

[Hint: 2MnO₄⁻ + 5H₂O₂ + 6H⁺ → 2Mn²⁺ + 5O₂ + 8H₂O]

Q18. A textile industry in Ahmedabad uses hydrogen peroxide for bleaching 1000 kg of cotton fabric. The bleaching process requires 5 g of pure H₂O₂ per kg of fabric.

(a) Calculate the total mass of pure H₂O₂ required.

(b) If the industry uses 30% H₂O₂ solution, calculate the mass of solution needed.

(c) If the cost of 30% H₂O₂ is ₹ 150 per kg, calculate the total cost. Why is H₂O₂ preferred over chlorine bleach in textile industries?