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SSC CPO General Science Chemistry Quick Guide

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SSC CPO General Science Chemistry Quick Guide

General Science Chemistry Quick Guide

shape Introduction

Chemistry is the branch of science which deals with study of matter and various changes it undergoes. General Science Chemistry is an important section in the various competitive exams primarily the recruitment exams (Banking, SSC, Railways, RRB ALP, RRB Group D,etc.) in India. This General Science Chemistry Quick Guide presents the basics and key points of various Chemistry topics.

shape Matter

States of Matter:


shape Concepts

Classification of Matter:

Matter:

  • It is defined as anything that occupies space and has mass.

  • At a given temperature, an element is in one of the three states of matter- Solid, Liquid or Vapour (Gas).


Solids:

  • Solids possess definite shape and volume, eg. metals, brick, etc.


Liquids:

  • They possess definite volume but no definite shape.

  • They can flow, so they are called fluids, e.g. water, milk, mercury, oil,etc.


Gases:

  • Gases have neither a definite volume nor definite shape.

  • They takes the volume and shape of the container. E.g.– air, oxygen, hydrogen, etc.

  • Melting point of a substance is the temperature at which its solid form changes to a liquid.

  • Boiling point is the temperature at which the liquid form of a substance changes to a gas.

  • A physical change is a change in matter that involves no chemical reaction.

  • The three types of physical changes are melting, evaporation and freezing.

  • Chemical Change A change in which the identify of the original substance is changed and new substances are formed is called a chemical change for example souring of milk, burning of paper, rusting of iron etc.

Atom:

  • An atom is the smallest unit of an element.

  • An atom has a central nucleus.

  • The nucleus carries a positive charge.

  • Electrons revolves around the nucleus.

  • Protons have a positive charge.

  • Electrons have a negative charge.

  • Neutrons have no charge.


Element:

  • Everything in the universe is made of a combination of a few basic substances called elements.

  • The element is the simplest form of matter composed of atoms having identical number of protons in each nucleus.


Compound:

  • A compound is a pure substance that contains atoms of two or more chemical elements in definite proportions that cannot be separated by physical means and are held together by chemical bonds.

Air and Water:
Air is colorless, odorless, tasteless, gaseous mixture, mainly contains nitrogen (approximately 78%) and oxygen (approximately 21%) with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.

  • Water consists of hydrogen and oxygen in the ratio of 2:1 by volume and 1:8 by mass. e.g. (\(H_2O\))

  • Hard water has bicarbonates, chlorides sulphates of Ca and Mg. This water is unfit for washing and use in industrial boilers.

  • Heavy water is deuterium oxide (\(D_2O\)), molecular mass = 20).

Substances and Chemical Compositions:

Common Name Chemical Name Composition Formula
Alum Potash Potassium, Sulphur, Aluminium, Hydrogen and Oxygen \(K_2SO_4Al_2(SO_4)_3\)
Bleaching Powder Calcium hypochlorite Calcium, Chlorine and Oxygen CaCl(OCl)
Blue Vitriol Copper sulphate Copper, Sulphur and Oxygen \(CuSO_4.5H_2O\)
Caustic Potash Potassium hydroxide Potassium Hydrogen, and Oxygen KOH
Chalk Calcium carbonate Calcium, Carbon and Oxygen \(CaCO_3\)
Caustic Soda Sodium hydroxide Sodium, Hydrogen and Oxygen NaOH
Baking Soda Sodium bicarbonate Sodium, Hydrogen, Carbon and Oxygen \(NaHCO_3\)
Common Salt Sodium chloride Sodium and Chlorine NaCl
Epsom Salt Magnesium sulphate Magnesium, Sulphur, and Oxygen \(MgSO_4. 7H_2O\)
Galena Lead sulphide Lead and Sulphur PbS
Green Vitriol Iron sulphate Iron, Sulphur and Oxygen \(FeSO_4. 7H_2O\)
Glauber’s salt Gypsum Sodium sulphate Calcium Sulphate dihydrate Sodium, Sulphur, Oxygen and hydrogen \(Na_2SO_4.10H_2O CaSO_4.2H_2O\)
Laughing gas Nitrous oxide Nitrogen and Oxygen \(N_2O\)
Lime water Calcium hydroxide Calcium, Hydrogen, and Oxygen \(Ca(OH)_2\)
Litharge Lead monoxide Lead and Oxygen PbO
Plaster of Paris Calcium sulphate hemihydrate Calcium, Sulphur, Hydrogen and Oxygen \(2CaSO_4.H_2O\)
Quartz Sodium silicate Sodium, Silica and Oxygen \(Na_2SiO_3\)
Quick lime Calcium oxide Calcium and Oxygen CaO
Red lead Triplumbic Lead and Oxygen \(Pb_3O_4\)
Sal ammoniac Ammonium Chloride Nitrogen, Hydrogen and chlorine \(NH_4Cl\)
Soda ash or washing soda Sodium carbonate Sodium, Carbon, Hydrogen and Oxygen \(Na_2CO_3.10H_2O\)
Soda bicarbonate Sodium bicarbonate Sodium hydrogen, Carbon and Oxygen \(NaHCO_3\)
White vitriol Zinc sulphate Zinc, Sulphur, Hydrogen and Oxygen \(ZnSO_4.7H_2O\)

Metals and Non-Metals:
There are two types of elements metals and non- metals.

Metals:

  • Elements which are hard, ductile, brittle, and malleable, possess lustre and conduct heat and electricity are termed metals.

  • Except Mercury and gallium, all metals are solid.


Non-Metals:

  • Non metals are electronegative elements which have a tendency to gain one or more electrons to form negative ions called anions.

  • Non metals are non lustrous and bad conductors of heat and electricity.


Occurrence of Metals:

  • Minerals are naturally occurring chemical compounds of fixed composition and characteristics. e.g., silicates, oxides, sulphides, and carbonates, etc.


Uses of Some Metals and Non-Metals Compounds:

  • Silver Nitrate (\(AgNO_3\)) is called lunar caustic and is used to prepare the ink used during voting.

  • Hydrogen Peroxide (\(H_2O_2\)) is used as an oxidising agent, bleaching agent, as an insecticide and for washing old oil paintings.

  • Ferric Oxide (\(Fe_2O_3\))is used in jeweller’s rouge.

  • Silver Iodide (\(AgI\))is used for artificial rain.

Fuels:

  • The substance, which produce heat and light on combustion are called fuels.

  • LPG (Liquified petroleum gas) is a mixture of hydrocarbons containing three or four carbon atoms, such as propane, butane and pentane.


Metals:

  • Coal is made up of carbon.

  • The common varieties of coal are anthracite, bitumen; lignite and peat.

  • Acids are chemical compounds that taste sour, turn blue litmus red, and often react with some metals to produce hydrogen gas.

  • Acids– \(HNO_3\), \(HNO_2\), \(H_2SO_4\), \(H_3PO_4\), \(H_3PO_3\), \(H_2CO_3\), etc.

  • Bases are chemical compounds that taste bitter, turn red litmus blue and feel slippery. Base: (NaOH), (\(Ca(OH)_2\)), (KOH), (RbOH), etc.

  • When aqueous (water) solutions of an acid and a base are combined, a neutralization reaction occurs.

  • The pH of a solution measures the hydrogen ion concentration in that solution.

  • Anything above pH 7 is alkaline, anything below pH 7 is considered acidic.

  • Human blood pH should be slightly alkaline (7.35-7.45).


Sources of Some Naturally Occurring Acids:

Acid Source
Citric acid Lemon, orange, grapes
Maleic acid Unripe apple
Tartaric acid Tamarind
Acetic acid Vinegar
Lactic acid Milk
Hydrochloric acid Stomach
Oxalic acid Tomato


Acidic & Basic Nature of Some Household Substances:

Acidic Basic (Alkaline)
1. Bathroom acid 1. Milk of magnesia (Antacids)
2. Vitamin C tablets (Ascorbic acid) 2. Toothpaste
3. Lemon juice 3. Soap solution or detergent solution
4. Orange juice 4. Solution of washing soda.
5. Tomato juice 5. Slaked lime & white wash
6. Vinegar
7. Fizzy drinks (Colas & Soda water)


pH Value of Some Important Substances:

Substance pH Value
Sodium Hydroxide: Alkaline 14.0
Ammonia 11.0
Baking Soda 8.3
Human Blood 7.35 to 7.45
Pure Water: Neutral 7.0
Milk: Acid 6.6
Tomatoes 4.5
Wine and Beer 4.0
Apples 3.0
Vinegar 2.2
Lemon Juice 2.0
Battery Acid 1.0
Urine(Human) 5.5 to 7.5
Tears 7.4
Sea water 8.5
Milk (Cow) 6.3 to 6.6
Coffee 5.0
Tooth paste 9.0

  • Plastics consist of very long molecules, each composed of carbon atoms linked into chains.

  • Polythene is composed of over 200000 carbon atoms.

  • Polymers are large long chain like molecules formed by the chemical linking of many smaller molecules.


Some Common Man-Made Polymers and Their Uses:

Polymer Use
Polythene Packaging material, carry bags, bottles etc.
Polypropene Bottles, Crates etc.
Polyvinyl chloride (PVC) Pipes insulation
Nylon (Polyester) Fibres, ropes etc
Teflon Nonstick kitchen wares
Vinyl rubber Rubber erasers
Polystyrene Foam Thermocole
Poly (Styrene butadiene) Rubber bubble gum
Bakelite Electrical insulation buttons
Lexan Bullet proof glass
Melamine Crockery

  • Radioactivity is discovered by French physicist Henry de Becquerel in 1896, who observed that uranium mineral gave off invisible radiation.

  • Radiations are of three kinds: Alpha, Beta and Gamma

  • Alpha (α) Particle is positively charged helium atom that has very little penetrating power.

  • Beta (β) Particles These are negatively charged light particles.

  • Gamma (γ) Particles These are electromagnetic radiations of low wavelength, high frequency, and high energy.

  • It is a process of plating one metal onto another by electrolysis, most commonly for decorative purposes or to prevent corrosion of a metal.

  • Types of electroplating capsopper plating, silver plating, and chromium plating, etc.

Carbon and Its Compounds:

  • All organic compounds contain carbon, and the vast majority also contains hydrogen bonded to carbon.

  • It is non-metal
  • .

  • Its atomic number is 6 and mass is 12.


Allotropes:

  • Allotropes are substances which have same chemical properties but different physical properties.


Glass is a mixture of an alkali silicate with the silicate of a base, that is, silica, sodium silicate and calcium or lead silicate.

Type and Uses:

  • Milky Glass is used to the melt glass.

  • Flint Glass, used in lenses, prisms.

  • Soda or Soft Glass is used for making bottles, window panes, etc.

  • Potash Glass or Hard Glass is used for making beakers, flasks, funnel, etc.

  • Crown Glass is used for optical apparatus.

  • Crook’s Glass is used for spectacles as it absorbs UV rays.

  • Glass Laminates is used to make windows and screens of cars, trains and aircraft.

  • Jena Glass is used for making laboratory bottles, for keeping acids and alkalies.

Soaps and Detergents: Soaps are the sodium or potassium salts of fatty acids.

Antibiotic: Medicinal compounds produced by moulds and bacteria, capable of destroying or preventing the growth of bacteria in animal systems. For example penicillin, chloramphenicol etc.

Antibody: Kinds of substances formed in the blood, tending to inhibit or destroy harmful pathogens, etc.

Antigen: Substance capable of stimulating formation of antibodies in a host. For example bacteria, virus etc.

Antipyretic: A substance used to lower body temperature.

Sulphadrugs: Alternatives of antibiotics, sulphanilamide, sulphadiazine, Sulpha gunamidine.

Antacids: Substances which neutralise the excess acid and raise the pH to appropriate level in stomach are called antacids.

Chloroform: A sweetish, colourless liquid. It is used as a solvent and anaesthetic.

Saccharin: A white crystalline solid which is 550 times sweeter than sugar, but does not have any food value. It is used by diabetic patients.

DDT: Dichloro diphenyl tricholoro ethane, a white powder used as an insecticide.

Branches of Science:

Branch Terminology
Adenology Study of glands
Angiology study of blood flow and lymphatic system
Arthrology Study of joints
Barology Study of gravitation
Bromatology Study of food
Carpology Study of fruits and seeds
Cetology study of whales and dolphins
Cosmology Study of the universe
Craniology Study of the skull
Dactylography The study of fingerprints
Demology Study of human behaviour
Ecology Study of environment
Endocrinology Study of ductless glands
Entomology Study of insects
Geology Study of earth’s crust
Hematology Study of blood
Hepatology Study of liver
Herpetology Study of reptiles and amphibians
Hypnology Study of sleep; study of hypnosis
Ichthyology Study of fish
Irenology The study of peace
Kalology Study of beauty
Laryngology Study of larynx
Mastology Study of mammals or mammary glands or breast diseases
Meteorology Study of weather
Myology Study of muscles
Neonatology Study of newborn babies
Nephrology Study of the kidneys
Obstetrics Study of midwifery
Odontology Study of teeth
Oncology Study of tumours
Pathology Study of disease
Pharmacology Study of drugs
Physiology Study of processes of life
Pyretology Study of fevers
Radiology Study of X-rays and their medical applications.
Seismology Study of earthquakes
Toxicology Study of poisons
Urology Study of urine; urinary tract
Virology Study of virusesstudy of viruses
Xylology Study of wood
Zoiatrics Veterinary surgery
Zoology Study of animals