Vidaara.orgClass 11 · Chemistry
CodeVID-C11-09-T3-01
Assignment — Hydrogen Peroxide & Hydrogen as Fuel
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Write balanced equations wherever required. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
The gas-phase dihedral angle in H2O2 is about:
- A.90°
- B.104.5°
- C.111°
- D.180°
2.
Hydrogen peroxide is industrially made by the:
- A.Haber process
- B.anthraquinone process
- C.contact process
- D.Ostwald process
3.
On decomposition, hydrogen peroxide gives water and:
- A.hydrogen
- B.ozone
- C.oxygen
- D.hydroxide
4.
Hydrogen peroxide is stored in:
- A.clear glass bottles in sunlight
- B.dark, wax-lined bottles
- C.open beakers
- D.metal cans
5.
In a hydrogen fuel cell, the only by-product is:
- A.CO2
- B.water
- C.NO2
- D.soot
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
Why is hydrogen peroxide called the open-book molecule?
7.
Write one reaction showing H2O2 as an oxidising agent.
8.
Give two reasons why dihydrogen is considered a clean fuel.
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
9.
Show with equations that hydrogen peroxide can act as both an oxidising and a reducing agent in acidic medium.
10.
Explain how a hydrogen–oxygen fuel cell generates electricity and why it is efficient.
Section D — Long Answer (5 marks)
1 × 5 = 5 marks
11.
Give an account of the preparation, structure, oxidising/reducing behaviour, storage and uses of hydrogen peroxide.
Answer Key
Section A — Multiple Choice Questions
- (C) 111°
- (B) anthraquinone process
- (C) oxygen
- (B) dark, wax-lined bottles
- (B) water
Section B — Short Answer (2 marks)
- Its two O–H bonds lie in two different planes that meet along the central O–O bond, so the shape resembles a half-open book; it is non-planar.
- 2Fe2+ + H2O2 + 2H+ → 2Fe3+ + 2H2O (Fe2+ is oxidised to Fe3+).
- Its combustion yields only water (no CO2 or soot), and it has a very high energy output per gram (about 143 kJ g−1), higher than petrol.
Section C — Short Answer (3 marks)
- As oxidiser: 2Fe2+ + H2O2 + 2H+ → 2Fe3+ + 2H2O. As reducer: 2MnO4− + 5H2O2 + 6H+ → 2Mn2+ + 5O2 + 8H2O. The dual behaviour arises because oxygen is in the intermediate −1 state.
- Hydrogen is oxidised at the anode and oxygen reduced at the cathode; the electrons flow through the external circuit as current and the ions combine to give water. Because the chemical energy is converted directly to electrical energy without a heat-engine step, the fuel cell is more efficient and the only product is water.
Section D — Long Answer (5 marks)
- Preparation: lab, BaO2·8H2O + H2SO4 → BaSO4 + H2O2 + 8H2O; industry, the anthraquinone (2-ethylanthraquinol) auto-oxidation process. Structure: non-planar open-book with a gas-phase dihedral angle of about 111° and O–O bond about 148 pm. Behaviour: oxygen in −1 state lets it oxidise (PbS → PbSO4; Fe2+ → Fe3+) and reduce (decolourises acidified KMnO4). Storage: in dark, wax-lined bottles, kept cool, with urea or phosphoric acid as stabiliser, since it decomposes to water and oxygen. Uses: antiseptic, mild bleach, restoring paintings, rocket propellant and pollution control.
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