Hydrogen And It's Compounds Formulas

In Hydrogen And It's Compounds concept, the most important formulas to be aware of are the Preparation of hydrogen, Properties of molecular hydrogen, Isotopes of hydrogen, and many more. Learn and remember all Hydrogen And It's Compounds Formulas by using the formulae sheet and tables provided here below.

1. Preparation of hydrogen:
(i) Passing steam over hot iron (Lane process)
3Fe + 4H₂O → Fe₃O₄ + H₂ ↑

(ii) By the action of water on hydrolith
CaH₂ + H₂O → Ca(OH)₂ + 3H₂

(iii) By the electrolysis of water

(iv) Bosch process

2. Properties of molecular hydrogen:
Metals like Pd, Pt, Ni, Co etc. adsorb large quantities of the gas due to vacancies between these atoms. This is known as “occlusion”.

3. Reaction with vegetable oils:

This process is known as “hydrogenation” or “hardening of oils”

3. Isotopes of hydrogen:

4. Different forms of hydrogen:
Atomic hydrogen:

Nascent hydrogen:
Zn + dil.H₂SO₄ → ZnSO₄ + 2H

Ortho and Para hydrogen:

• If two nuclei have same spin then it is called “Ortho H₂“.
• If two nuclei have different spin then it is called “Para H₂“.

5. HYDRIDES:
(i) Ionic or salt like hydrides: s block
Li H, NaH, KH. RbH, SrH₂, BaH₂ etc.
Be & Mg hydrides are covalent in nature

(ii) Molecular or covalent hydrides: p blcok
NH₃, PH₃, H₂O, CH₄ etc.

(iii) Metallic or Interstitial hydrides:
trasition elements
In these hydrides, hydrogen atoms occupies the interstitial position of
metallic lattice.
La H_2.87, Ti H_1.8, Zr H_1.9
Hydride gap = 7, 8, 9

6. Water:
(i) The existence of hydrogen bonding is responsible for high values of specific heat, the latent of fusion and latent heat of vapourisation and high boiling point.
(ii) Some of the covalent compounds such as alcohols, carboxylic acids and carbohydrates are soluble in water due to formation of hydrogen bonding.

7. Hardness of Water:
• temporary hardness of water is due to bicarbonates of Ca and Mg. It can be removed by –

• Boiling
• Clark method using CaO

• Permanent hardness of water is due to chloride/sulphate of Ca and Mg. It can be removed by –

• Adding washing soda, Na₂CO₃
• Calgon [Na₆(PO₃)₆]
• Permutit, Na₂ Al₂ Si₂ O₈. xH₂O
• Artificial resins, RSO₃H & RNH₂OH

8. Heavy water or Deuterium oxide (D₂O):

• It is produced by repeated electrolysis of ordinary water containing alkali.
• Most important use of heavy water is in nuclear reactors for slow down the speed of neutrons (i.e. as a moderator)

9. Hydrogen Peroxide
Preparation:

• BaO₂ . H₂O + H₂SO₄ → BaSO₄ + H₂O₂ + 8 H₂O
• Na₂O₂ + 2 H₂SO₄ → 2 Na₂SO₄ + H₂O₂
• BaO₂ + H₂O + CO₂ → BaCO₃ + H₂O₂
• Oxidation of 2Alkyl anthraquinol
• Electrolysis of 50% H₂SO₄

10. Chemical properties:
(a) Decomposition:

(b) H₂O₂ can accept as well can donate electrons and thus it can acts as an oxidising and reducing agent in acidic as well as alkaline medium

(c) Oxidising properties: It is a strong oxidising agent under acidic and alkaline conditions. Oxidation in acidic medium is generally slow while rapid in alkaline solution.
(i) In acidic solution:
H₂O₂ + 2H⁺ + 2e → 2 H₂O

(ii) In alkaline solution:
H₂O₂ + 2OH^–+ 2e → 2 H₂O + 2O^2-

(d) Reducing properties:
It acts as a reducing agent towards strong oxidising agents in acidic as well as alkaline medium. Reducing action in acidic solution is slower than in alkaline solution.

(e) Bleaching action:
H₂O₂ → H₂O + [O]

Structure:

Structure of H₂O₂ in the gas phase.

11. Tests of H₂O₂:
(a) It liberates iodine from KI solution in the presence of ferrous sulphate.

(b) It gives orange red colour with acidified titanium oxide due to formation of pertitanic acid.
Ti(SO₄)₂ + H₂O₂ + 2H₂O → H₂TiO₄ + 2H₂SO₄

(c) It gives blue colour with acidified K₂Cr₂O₇ and ether. The blue colour of chromium peroxide is stabilized by ether.
CrO₄^2- + 2H⁺ + 2H₂O₂ → CrO₅ + 3H₂O

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