These MP Board Class 11th Chemistry Notes for Chapter 9 Hydrogen help students to get a brief overview of all the concepts.

MP Board Class 11th Chemistry Notes Chapter 2 Structure of Atom

→ Hydrogen : Represents similarity with both alkali metals of I-group and halogens of VH-group.

→ Hydrogen has three isotopes : (1) Protium (1H1), (2) Deuterium ((1H2), (3) Tritium (1H3).

→ Ortho hydrogen : Nuclei of both hydrogen atoms of hydrogen molecule spin in the same direction.

→ Para hydrogen : Nuclei of both hydrogen atoms of hydrogen molecule spin in the opposite direction.

→ Water : Exist in three states on earth : (1) Solid, (2) Liquid, (3) Vapour.

MP Board Class 11th Chemistry Notes Chapter 9 Hydrogen

→ Structure of water molecule : Angular V-shape, H – O – H bond angle is 104°27′. Density of ice less than water and maximum density of water is at 4°C.

→ Hardness of water: Hardness of water is of two types : (1) Temporary hardness, (2) Permanent hardness.

→ Temporary hardness : Due to soluble bicarbonates of Ca and Mg.

→ Permanent hardness : Due to soluble chlorides and sulphates of Ca and Mg.

→ Hard water : Produce less lather slowly with soap.

→ Heavy water : D20, as a neutron moderator.

→ Ionic hydrides are also known as Saline hydrides.

→ Tritium (1H3) is radioactive in nature. It emits low energy β-particles (t1/2 = 12-33).

→ Hydrogen is prepared in the laboratory by the action of dilute HCl on granulated zinc.

→ Bond enthalpy of H – H bond in H2 is 435.88 kJ mol-1, which is maximum in single bond.

MP Board Class 11th Chemistry Notes Chapter 9 Hydrogen

→ Hydrogen combines with elements to form hydrides. Hydrides are of three series :
(i) Ionic or Saline hydrides, (ii) Covalent or Molecular hydrides, (iii) Metallic or Interstitial hydrides.

→ Metallic hydrides are used in the purification of dihydrogen and in storage of hydrogen and as an energy source.

→ Dihydrogen is used in the manufacture of ghee from oil, in reduction in metal extraction, as a rocket fuel.

→ Dihydrogen is the basis of hydrogen economy, transport and storage of hydrogen as a liquid or gas H2 in the form of energy. Main advantage of hydrogen economy is the observation of H2 in the form or energy. Presently, it is used in the manufacture of electrical energy and in fuel cells,

→ High heat of evaporation and heat capacity of water is responsible for maintaining the body temperature of organisms and climatic conditions.

→ Due to the formation of hydrogen bond with polar molecules, covalent compounds like alcohol, carbohydrates are also soluble in water.

→ Due to bent structure molecules of water are extremely polar.

→ Hydrogen bond is maximum in ice and minimum in water vapour.

MP Board Class 11th Chemistry Notes Chapter 9 Hydrogen

→ Water which forms lather with soap is called soft water. Water which does not give lather is called hard water.

→ Temporary hardness of water is removed simply by boiling.

→ Treatment of permanent hardness of water is done by washing soda method, calgon process, ion exchange method or synthetic resin process.

→ 30% solution of H2O2 is known as perhydrol which is used as an insecticide and antiseptic.

→ 20% volume H2O2 means by the decomposition of 1 ml of it at NTP 20 ml oxygen is obtained.

→ H2O2 behaves as an oxidizing, reducing and bleaching agent. Its bleaching property is due to oxidation.

MP Board Class 11th Chemistry Notes Chapter 9 Hydrogen

→ H2O2 is stored in plastic or glass container sealed with wax in the dark because it decomposes by the effect of light. Presence of surface of metal and minute quantity of base catalysis its decomposition.

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