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Wednesday, 2 September 2015

Chemistry Definitions

                                Chemistry Definitions:




Acid rain:
Acid rain is formed by dissolving acidic air pollutants such as sulphur dioxide and nitrogen dioxide by rain water.

Acidic salts:
Acidic salts are formed by partial replacement of a H+ ion of an acid by a positive metal ion.

Alkanes:
Alkanes are the simplest hydrocarbons in which each carbon is attached through single bonds with other atoms, They have general formula CnH2n+2.

Alkenes:
Alkenes are unsaturated hydrocarbons having double bonds. They have general formula CnH2n.

Alky radicals:
They are the derivatives of alkanes. They are formed by the removal of one hydrogen atom form an alkane molecule.

Alkynes:
Alkynes are unsaturated hydrocarbons having a triple bond in their molecules. They have a general formula CnH2n-2.

Amino acids:
Amino acids are organic compounds consisting of both amino and carboxyl groups.

Ammonical liquor:
Ammonical liquor is a solution of ammonia gas in water.

Amphoteric:
Amphoteric is a substance that can behave both as an acid and as a base.

Arrhenius acid:
It is a substance that contains hydrogen and produces H+ ions in aqueous solution.

Arrhenius base:
It is a substance that contains hydroxyl and produces Hydroxide OH- ions in aqueous solution.

Atmosphere:
It is the envelope of different gases around the Earth. It extends continuously from the Earth's surface outwards without any boundary.

Basic salts:
They are formed by the incomplete neutralization of a polyhydroxy base by an acid.

Bronsted-Lowry base:
It is a substance that can accept a proton from another substance.

Bronsted-Lowry acid:
It is a substance that can donate a proton to another substance.

Capillary action:
It is the process by which water rises up from the roots of plants and leaves.

Carbohydrates:
They are macromolecule defined as polyhydroxy aldehydes or ketones or the organic compounds which produce polyhydroxy aldehydes or ketones on hydrolysis.

Catenation:
It is the linking of carbon atoms with one another through covalent bonds to form long chains or rings of carbon atoms.

Chemical equilibrium state:
It is one at which forward reaction and reverse reaction takes place at equal rates but in opposite direction.

Coal gas:
It is the mixture of hydrogen, methane and carbon monoxide.

Coal:
It is blackish complex mixture of compounds of carbon, hydrogen and oxygen.

Coal tar:
It is a thick black liquid. It is a mixture of more than 200 different organic compounds, mostly aromatic.

Coke:
It is 98% carbon. It is left behind as a residue of coal.

Concentration:
It is a separating technique in which mineral is separated from gangue depending upon their wetting abilities.

Crude oil:
It is a dark brownish viscous liquid.

Destructive distillation:
It is strong heating of coal in closed retorts in the absence of air.

Dynamic equilibrium state:
It is one at which reaction does not stop, rate of forward and reverse reactions becomes equal to each other but take place in opposite direction.

Equilibrium constant:
It is a ratio of concentration of products raised to the appropriate power of coefficient to the product of concentration of reactants raised to the appropriate power of coefficient as expressed in the balanced chemical equation.

Fatty acid:
They are the building blocks of lipids. They are long chain saturated or unsaturated carboxylic acids.

Functional group:
It is defined as an atom or group of atom which gives characteristic properties to organic compounds.

Green house effect:
It is the rising of temperature because of trapping of heat energy by carbon dioxide gas in the atmosphere.

Hard water:
It does not produce lather with soap.

Hydrocarbon:
They are the compounds made up of only two elements carbon and hydrogen.

Hydrogenation:
It means addition of hydrogen in alkenes and alkynes.

Irreversible reaction:
Those reactions in which products do not recombine to form reactants.

Industrial waste:
It is the by-products discharged either to open ground or to water channels.

Law of mass action:
It states rate of a chemical reaction is directly proportional to the product of the concentrations of its reactants raised to power equal to their number of moles as in the balanced chemical equation.

Lewis acid:
It is a substance that can accept a pair of electrons.

Lewis base:
It is a substance that can donate a pair of electrons.

Lipids:
They are macromolecules made up of fatty acids.

Mesosphere:
It is next to stratosphere and extends up to 85 kilometers from the Earth's surface.

Metallurgy:
It is the technique in which metals are extracted from their ores by applying different operations.

Mineral:
It is a naturally occurring substance that contains a metal to be extracted.

Monosaccharides:
They are the simplest sugars, which cannot be hydrolyzed. They consists of 3 to 9 carbon atoms.

Natural gas:
It is a mixture of low molecular mass hydrocarbons. The main component about 85 % is methane, other gases are ethane, propane, and butane.

Normal salt:
They are formed by the total replacement of ionizable H+ ions of an acid by a positive metal ion or NH4+ ion.

Oligosaccharides:
They give 2 to 9 units of monosaccharides on hydrolysis.

Ore:
It is a natural deposit containing mineral of an element to be extracted.

Organic compound:
They are compounds of carbon and hydrogen and their derivatives.

Ozone hole:
It is the region in which ozone layer depletes in atmosphere.

Ozone:
It an allotrope of oxygen. Its maximum concentration called ozone layer lies in stratosphere region about 25 to 30 km away from Earth's surface.

Permanent hardness:
It is because of presence of sulphates and chlorides salts of calcium and magnesium.

Pesticides:
They are dangerous organic chemicals used to kill or control pests.

Petroleum:
It is a dark brownish or greenish black colored viscous liquid.

pH:
It is the negative logarithm of molar concentration of the hydrogen ions.

Pollutants:
They are waste materials that pollute air, water  or soil.

Polysaccharides: 
Are the carbohydrates consisting of hundreds to thousands of monosaccharides.

Primary pollutants:
Are the waste or exhaust products driven out because of combustion of fossil fuels and organic matter.

Proteins:
These are highly complicated nitrogenous compounds made up of amino acids.

Reduction:
It means addition of nascent hydrogen.

Refining:
It is the process of separation of crude oil mixture into various useful products. It is carried out by a process called fractional distillation.

Reversible reaction:
Are those in which products can recombine to form reactants.

Roasting:
It is the heating of concentrated ore in a furnace in the presence of air.

Salt:
It is defined as an ionic compound composed of a metallic cation and non metallic anion.

Saturated hydrocarbon:
They are the compounds in which all the four valencies of carbon atoms are fully satisfied by single bond with other carbon atoms and hydrogen atoms.

Secondary pollutants:
These are produced by various reactions of primary pollutants with water.

Smelting:
It is further heating of the roasted ore, flux of sand and coke in a blast furnace in the presence of excess of air.

Soft water:
It is that produces good lather with soap.

Stratosphere:
It is the region that covers the atmosphere from 12 to 50 kilometers.

Strong acids and bases:
Are those compounds that can ionize completely.

Substitution reaction:
In this one or more hydrogen atoms of a saturated compound are replaced with some other atoms.

Temporary hardness:
It is because of presence of bicarbonates of calcium and magnesium.

Thermosphere:
It  lies beyond mesosphere. In this region temperature rises gradually.

Troposphere:
It is just above Earth's surface and extends up to 12 kilometers.

Unsaturated Hydrocarbon:
These are the compounds in which the two carbon atoms are linked by a double or a triple bond.

Water borne diseases:
These are caused by drinking polluted water or eating food prepared with polluted water.

Water softening:
It is the removal of hard water ions(Mg2+, Ca2+).

Weak acids and bases:
They ionize partially in water.

Written by: Asad Hussain.


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