- Combustion fully oxidises carbon compounds, breaking all chemical bonds and producing CO₂ and H₂O.
- Oxidising agents like potassium permanganate or potassium dichromate can convert alcohols to carboxylic acids.
- Air inlets in stoves ensure complete combustion; black soot indicates incomplete combustion and fuel wastage due to blocked air inlets.
Definitions [9]
Definition: Hydrogen
Hydrogen is the first and lightest element in the periodic table. It is the most abundant element in the universe, constituting about 70% of the total mass of the universe and 91% of total atoms.
Define catalytic hydrogenation.
catalytic hydrogenation is a process by which hydrogen gas is passed through vegetable oils in the presence of catalyst like Ni, Pt or Pd to convert them into solid vanaspati ghee.
Define oxidation number.
The oxidation number of an element is defined as the formal charge that an atom of that element appears to have when electrons are counted.
Define an oxidation reaction.
The chemical reaction in which reactants gain oxygen to form the corresponding oxide. Also, A chemical reaction in which reactants lose hydrogen to form a product is called oxidation.
Example: \[\ce{H2S + Cl -> 2HCl + S}\]
Define reduction.
Those reactions in which hydrogen combines with a substance or oxygen is removed from a substance, are known as reduction reactions.
Example: \[\ce{2HgO->[heat]2Hg +O2}\]
Define corrosion.
When a metal is attacked by substances around it, such as moisture, acids, etc., it is said to corrode, and this process is called corrosion.
Corrosion is an electrochemical process in which a metal is oxidised to a metal oxide or another salt of the metal by losing electrons to oxygen or another electronegative element, forming a coating on the metal surface.
Definition: Oxidation Reaction
The chemical reaction in which a reactant combines with oxygen or loses hydrogen to form the product is called oxidation reaction.
Definition: Oxidants or Oxidising Agents
Chemical substances which bring about an oxidation reaction by making oxygen available are called oxidants or oxidizing agents.
OR
Substances that can give oxygen to other substances are called oxidants or oxidizing agents.
Define redox reaction.
Redox reactions are those in which reduction and oxidation both takes place simultaneously i.e. one substance is reduced while the other gets oxidised.
Key Points
Key Points: Hydrogen
- Electronic configuration: 1s¹ — it exists as a diatomic molecule H₂ called dihydrogen.
- Hydrogen does not belong to any group definitively; it resembles both alkali metals (loses 1 electron) and halogens (gains 1 electron).
- Alkali metals have oxidation number +1, and alkaline earth metals have oxidation number +2 in all their compounds.
Isotopes of Hydrogen:
| Isotope | Symbol | Atomic Number (Z) | Atomic Mass (A) | Natural Abundance |
|---|---|---|---|---|
| Protium |
\[_1^1HorH\] |
1 | 1 | 99.98% (naturally occurring) |
| Deuterium | \[_1^2HorD\] | 1 | 2 | 0.02% (naturally occurring) |
| Tritium | \[_1^3HorT\] | 1 | 3 | Trace (radioisotope) |
Uses of Hydrogen:
- Hydrogenation of oils to convert them into solid fats (Vanaspati ghee)
- Liquid dihydrogen is used as a rocket fuel
- Production of ammonia (Haber process)
- In production of methanol (from CO)
Key Points: Oxidation
Concepts [12]
- Position of Hydrogen in Periodic Table
- Similarities Between Hydrogen and Alkali Metals
- Similarities Between Hydrogen and Halogens
- Hydrogen
- Preparation of Hydrogen
- Application of Activity Series in the Preparation of Hydrogen
- Recognition and Identification of Gases
- Manufacture of Hydrogen
- Physical Properties of Hydrogen
- Chemical Properties of Hydrogen
- Uses of Hydrogen
- Chemical Properties of Carbon Compounds > Oxidation
