General Chemistry Notes-4

Calcination is heating strongly in the absence of air. Roasting is heating in the excess of air . Smelting, also called autoreduction, involves reduction of ores, usually oxides at elevated temperatures.

It is difficult to remove the earthy matter called gangue which contaminates an ore. This is done by adding to ore a substance called flux. Flux combines with gangue to form a molten product called slag, which can be easily removed.

An alloy is a mixture of two or more metals and is homogeneous in nature. For example Brass (Copper, Zinc), Bronze ( Copper, Tin) and Gun Metal ( Copper, Tin and Zinc) are examples of alloys.

An amalgam is a solution of metal in mercury. Sodium amalgam is used a reducing agent. Tin amalgam is used for making mirrors. Cadmium and Gold amalgam are used in dentistry.

A few elements like arsenic, Antimony, Boron, Silicon and Germanium behave both like metals and non-metals. These are called metalloids.

The five main causes of air pollution are carbon monoxides, nitrogen oxides, hydrocarbons and sulphur oxides. Transportation sources are responsible for 74% of all carbon monoxide emissions. Use of Catalytic converter in two stages helps in eliminating pollutants from exhaust gases before they are discharged into atmosphere. In the first stage converter, Nitrogen Oxide is converted to Nitrogen and Ammonia in the presence of finally divided Platinum as a catalyst. In the second stage coverter, Hydrocarbons and carbon monoxide are completely oxidized to water and carbon dioxide in the presence of Platinum catalyst. Unleaded gasoline should be used as Platinum can be poisoned by the lead.

Much of Nitrogen Oxides and Sulphur Oxides entering into the atmosphere are converted into Nitric acid and Sulphuric acid. This will generate precipitation known as acid rain.

Urea is used as a fertilizer. DDT ( Dichloro-Di-Phenyl Trichloro Ethane) and BHC ( Benzene HexaChloride) , Melathion and parathion are used as pesticides. Zinc Phosphate and Barium Carbonate are used as rodenticides. Bordeaux Mixture ( copper Sulphate + Lime + Water) are used as fungicides.

General Chemistry Notes-3

Chemistry Notes-3

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1. Ammonia is manufactured by the Haber Process

2. Full Name of TNT, an explosive is Trinitrotoluene

3. Trinitrophenol, which is used as an explosive and antiseptic is also known as Picric Acid.

4. Nessler’s Reagent is used for the test of Ammonia and Ammonium Salt. It gives brown precipitates

5. Nitric Acid ( HNO3) is manufactured by Electric Arc Process.

6. The process of Petroleum refining is called as a fractional distillation

7. There are various products having different boiling points which are obtained during fractional distillation. At a boiling point of 30 to 70 celcius there is Petroleum Ether which is used as solvent for drycleaning. At a boiling point of 70 to 120 degrees celcius, there is Petrol or gasoline which is used as a motor fuel and general solvent. At a boiling point of 120 to 150 degrees celcius, there is Benzoline which is also a solvent. Then there is Kerosene at 150 to 300 degrees celcius which is used as an illuminant and as a fuel. And Finally above 300 degrees celcius as boiling point, we have Lubricating oil, vasaline and paraffin wax which are used as lubricant, grease and wax.

8. Petrol is obtained by a process called cracking. In this process kerosene and crude oil are broken up into low boiling point hydrocarbons such as Octane and Heptane.

9. To prevent knocking in petrol engine, an antiknock agent such as Tetraethyl lead is added. Now in lead free oils it is not used as it also harms catalytic converters.

10. Iron commonly have three forms, first form which is the crudest form is cast iron containing 2 to 5 percent carbon. Then there is steel which has 0.15 to 1.5% of carbon. Wrought iron is the purest form of iron having 0.12 to 0.25 percent of carbon.

11. On exposure to moist air, in the presence of carbon dioxide, iron is converted into brown hydrated iron oxide ( Fe2O3. 10 H2O). This process is called rusting.

12. Stainless steel contains 13% chromium.

13. Acids are generally sour, turn blue litmus red and generally give hydrogen with metals.

14. An acid is a substance which furnishes H+ ion on dissolving with water. It is proton donor and an electon acceptor.

15. Bases react with Acids to produce salt and water. They turn red litmus blue. They are also called alkalies eg. NaOH.

16. A base is defined as proton acceptor and an electron donor.

17. pH is negative logarithm of H ions. pH of neutral solutions is 7. For acidic solutions, pH is between 0 and 7 and for alkaline solutions it is between 7-14.

18. Metals occur in nature as chemical compounds called minerals. If these minerals are used as the starting material for extracting the metal, they are called ores.

Teeth and Bones

Teeth

-In lower vertibrates, the teeth are replaced continuously. This condition is called Polyphyodonty.

- Diphyodont is a condition in which there are only 2 definite sets of teeth.

Teeth Types

Incisiors are used for cutting and biting. Canines are used for stabbing. Premolars are used for cutting and Molars  are used for grinding.

Dental Formula:  Dental formula for Milk set for man is 2120/2120= total 20 teeth. For an adult man the dental formula is 2123/2123= Total 32 teeth.

Dental Trivia

1. First Milk Teeth to appear are Incisors while the first permanent teeth to appear is 1st Molar.

2. First Molar is the largest of all teeth while the third molar (last) which is also called the wisdom toot is the smallest.

3. Tusks of Elephats are modified incisor teeth.

4. African Elephants, both males and females have tusks while in India only males have them.

5. The prolonged teeth of Wild Boars are modified Canine Teeth.

Human Bones

The bone of brain box is called Cranium, Cheek bone is called Zygomatic bone, Upper jaw bone is called Maxilla, that of lower jaw is called Mandible. Collar bone is called Clavicle, Shoulder bone is called Scapulla, Hip Bones are named as Ilium, Ischium and Pubic. Knee bone is called Patella, chest bones are called Pectoral Glands, waist bones are called pelvic girdles. Upper arm bone is called Humerus, fore-arm bone are called Radius and Ulna. Wrist bones are called Carpals and Palm Meta Carpals. Finger bones are called Phalanges, thigh bone is called Femur, shank bones are called Tibia and Febula. Ankles are called Tarsals, sole bones are called meta tarsals, Foot-fingers are called phallanges and Sessamoid.

Bones Trivia

1. At the time of birth, the total of bones are 350 while in adults it is 206.

2. Each bone meets with other except Hyoid bone ( U-shaped) at the neck. It is helpful in crime identification.

3. Femur is the longest bone.

4. Vertebre are 26 bones in number

5. Stapes in tthe inner ear is the smallest bone.

Bone joints are of three types , Non-Movable as that found in Skull, Slightly movable as that found in Vertebra and Movable as found in hip and shoulder joints.

Chemistry Notes for Prelims-2

Deliquescence and Efflorescence

* Solids like NaOH and Cacl₂ become damp on exposure to moist air. Such substances are called deliquescent substances.

* On the other hand, crystals of washing soda loses a part of water of crystallisation (Na₂CO₃ . 10 H₂O) and crumble into powder. Such substances are called efflorescent substances. 

_{FIRE EXTINGUISHERS} 

Two methods of extinguishing a fire are:

a. Cutting off the supply of air.

b. Cooling the flames below the ignition temperature.

types:

Ordinary: Mixture of Water and CO₂ 

Foam Type: Fire covered by foam of oil and Sodium Bicarbonate.

Electrical Fires: Heavy Carbon Tetrachloride is put on fire.

COMBUSTION: It is the process of burning accompanied by the liberation of heat and light.

* It may take place in the presence of gases which support combustion eg.Oxygen or Chlorine.

* Farther the substance which burns must be raised to a particular temperature called ignition temperature.

EXPLOSION: It is sudden expansion of gases with a loud noise, owing to release of internal energy.

COMPOSITION OF AIR: Nitrogen: 78%, Oxygen: 21%, Argon: 0.9%

* Air is only a mixture and is not a compound.

* Oil contains unsaturated compounds. They add hydrogen and are converted into solid fats. This hydrogenation of oil is called 'vanaspati'.   

Peculiar Properties of Water: Even though molecular weight of water is low, it has unusually high boiling point. It is denser than ice.

Solid CO₂ used in refrigerators is called dry ice.

Carbonic Acid  is also known as soda water.

A Fuel is a substance that is used to produce heat energy.

Carbon Cycle: During day time , plants take up CO₂ from air and return oxygen. At night the plants take in oxygen and gives out CO₂. This cycle serves to maintain the % of  CO₂ in air fairly constant.  

Gobar Gas: Obtained by fermentation of cow dung and water, inside a pit in the absence of air, also called 'biogas' used for running cooking, tubewells etc.

Aqua Regia: A mixture of Conc. HCl and conc. HNO₃ in the ratio of 3:1 is called aqua regia. It can dissolve Gold and Platinum.

Laughing Gas: Nitrous Oxide: When inhaled, produce laughing. Used as anesthetic   

Notes on General Chemistry-1

CHEMISTRY

SCOPE OF CHEMISTRY:

Deals with matter and the changes that matter undergoes when subjected to the action of heat light, electricity and other matter.
Elements: Substance which cannot be subdivided by any physical or chemical method.
Metals: Silver, Gold, copper sodium etc
Non metals: Oxygen, hydrogen sulphur etc.
Mixtures and compounds :
Iron + Sulphur = Mixture – Possesses both properties of iron and sulphur.
Iron + Sulphur-------------- Heated----FeS--- Compound- Properties of Iron and sulphur are lost.

Kinetic Theory of Matter: It says the pressure of a gas as due to bombardment of the wall of the vessel by the molecules of the gas.

Chemical Reactions:
Decomposition: (AB-------------- A+B)
Combination: (A + B--------------AB)
Double decomposition: (AB + CD----------- AD+ BC)
Displacement: (A +BC---------------- AC + B )

If the heat is evolved in a reaction it is called exothermic if heat is absorbed it is endothermic reaction.

ATOMIC STRUCTURE:
First given by John Dalton : says atom is indestructible.

Nucleas: Rutherford. The entire mass is concentrated in the nucleus which contain protons and neutrons, their total number equal to atomic mass.

The atomic number which is net positive charge on nucleus is equal to the number of protons.
Since the atom is electrically neutral , a number of electrons is equal to the number of the protons revolve around the nucleus.

Chemical Bonding: The force of attraction which binds the atoms in a molecule is called Chemical bonding.

Isotopes: They are atoms of the same element having the same atomic number but different atomic masses. They differ in the number of neutrons in the nucleus.

Nuclear fission: When certain heavy atoms like Uranium are bombarded with high velocity neutrons, new fast moving neutrons are released along with a large amount of energy. This process is called neuclear fission.

If all the neutrons are used in producing more fission a rapid and violent reaction takes place. This is the basis of the atomic bomb.

Nuclear Fusion: The two isotopes of hydrogen eg. Deutruim and Tririum react to produce, helium, neutron and a flood of energy. This is called fusion, and forms the basis of H-bomb.

Oxidation and Reduction:
Occur side by side.
Wherever there is oxidation, there is reduction.
When Chlorine oxidized Hydrogen sulphide to Sulphur, Hydrogen Sulphide reduces Chlorine to Hydrogen Chloride. Cl2 + H2S--------------- 2HCl + S

Oxidation: Removal of hydrogen or addition of oxygen or removal of electrons.
Reduction: Addition of hydrogen or removal or oxygen or addition of electrons.

Mathces: Side of the Box: Red phosphorous or phosphorous trisulphide.
Match Sticks: Impregnated with borax- so that they can be extinguished without glowing for a long time.

Heavy Water:
Discovered by Urey.
Contains heavy hydrogen atom i.e deuterium(D)
Formula D2O
Density 1.106

Used in Nuclear reactors to absorb neutrons