Carbon and its Compounds online mcq quiz
Carbon and its Compounds boostup points
➥ Introduction
☞ Compounds are of two types:
☞ Organic Compounds
☞ Organic Compounds are made up of Carbons and form the basis of all living organisms
➥The Covalent Bond
☞ Carbon always forms covalent bond.
☞The bonds formed by sharing of electron pair between two atoms are known as covalent bonds.
➥ Noble gas configuration of Carbon
☞ Carbon is tetravalent, it does not form ionic bond by either losing four electrons (C4+) or by gaining four electrons (C4-).
☞ It is difficult to hold four extra electrons and would require large amount of energy to remove four electrons. So, carbon can form bond by sharing of its electrons with the electrons of other carbon atom or with other element andattain noble gas configuration.
☞ The atoms of other elements like hydrogen, oxygen and nitrogen, chlorine also form bonds by sharing of electrons.
➥Physical Properties of Covalent Compounds
☞ Covalent compounds have low melting and boiling points as they have weak intermolecular force.
☞They are generally poor conductor of electricity as electrons are shared between atoms and no charged particles are formed.
☞ Versatile Nature of Carbon: The two characteristic properties of carbon element which lead to the formation of large number of compounds :
☞ Catenation: Carbon can link with carbon atoms by means of covalent bonds to
form long chains, branched chains and closed ring compounds.
☞ Carbon atoms may be linked by single, double or triple bonds.
☞ Tetravalency: Carbon has 4 valence electrons.
➥ Hydrocarbons: Compounds made up of hydrogen and carbon are called hydrocarbon.
☞ There are two types of Hydrocarbons.
1. Saturated Hydrocarbons
☞Single bond between carbon atoms.
☞ ã…¡Cã…¡Cã…¡
☞ Alkanes are saturated hydrocarbons.
☞ General Formula: CnH2n+2
2. Unsaturated Hydrocarbons
☞ Double or triple bond between carbon atoms.
☞ Alkenes and Alkynes are unsaturated hydrocarbons.
☞ Alkenes: ã…¡C＝Cã…¡
☞ General formula: CnH2n
☞ Alkynes: ã…¡C≡Cã…¡
☞ General Formula: CnH2n-2
➥Functional Groups
☞ In hydrocarbon chain, one or more hydrogen atom is replaced by other atoms in accordance with their valancies.
☞ These heteroatom or group of atoms which make carbon compound reactive and decide its properties are called functional groups.
➥Homologous Series:
☞ It is series of compounds in which the some functional group substitutes for the hydrogen in a carbon chain.
☞ Example: Alcohols – CH3OH, C2H5OH, C3H7OH, C4H9OH
☞ They have same general formula.
☞ Any two homologues differ by – CH2 group and difference in molecular mass is 14μ.
☞ They have same chemical properties but show gradual change in physical
properties.
➥Rules for nomenclature of organic compounds
1.Identify the longest carbon chain. This chain is called the parent chain.
2. Identify all of the substituents (groups appending from the parent chain).
3. Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When comparing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name.
4. If the same substituent occurs more than once, the location of each point on which the substituent occurs is given. In addition, the number of times the substituent group occurs is indicated by a prefix (di, tri, tetra, etc.).
5. If there are two or more different substituents they are listed in alphabetical order using the base name (ignore the prefixes). The only prefix which is used when putting the substituents in alphabetical order is iso as in isopropyl or isobutyl. The prefixes sec- and tert- are not used in determining alphabetical order except when compared with each other.
6. If chains of equal length are competing for selection as the parent chain, then the choice goes in series to:
a) the chain which has the greatest number of side chains.
b) the chain whose substituents have the lowest- numbers.
c) the chain having the greatest number of carbon atoms in the smaller side chain.
d) the chain having the least branched side chains.
7. A cyclic (ring) hydrocarbon is designated by the prefix cyclo-which appears directly in front of the base name.
➥Chemical Properties of Carbon Compounds
Combustion
☞ Carbon and its compounds are used as fuels because they burn in air releasing lot of heat energy.
☞ Saturated hydrocarbon generally burn in air with blue and non-sooty flame.
☞ Unsaturated hydrocarbon burns in air with yellow sooty flame because percentage of carbon is higher than saturated hydrocarbon which does not get completely oxidized in air.
Oxidation
☞ Alcohols can be converted to carboxylic acid in presence of oxidizing agent alkaline KMnO4 (potassium permangnate) or acidic potassium dichromate.
Addition Reaction
☞ Unsaturated hydrocarbons add hydrogen in the presence of catalyst palladium or nickel. Vegetable oils are converted into vegetable ghee using this process.
☞ It is also called hydrogenation of vegetable oils.
➥ Important Carbon Compounds: Ethanol and Ethanoic acid
Physical Properties of Ethanol
☞Colorless, pleasant smell and burning taste
☞Soluble in water
☞ Volatile liquid with low boiling point of 351 K
☞ Neutral compound.
Chemical Properties of Ethanol
☞ Reaction with Sodium
This reaction is used as a test for ethanol by evolution of H2 gas (Burn with pop sound).
☞Dehydration
Physical Properties of Ethanoic acid
☞ Colorless liquid having sour taste and have smell of vinegar.
☞ Boiling point is 391 K.
☞ When pure CH3COOH is freezes, it forms colorless ice like solid. So it is
called glacial acetic acid.
Chemical Properties of Ethanoic Acid
☞ Esterification
☞ Reaction with base
☞ Reaction with carbonates and hydrogen carbonates
➥Soaps and Detergents
☞ Soap is sodium or potassium salt of long chain carboxylic acid. Example:
C17H35COONa+
☞ Soaps are effective only in soft water.
☞ Detergents are ammonium or sulphonate salt of long chain of carboxylic acid.
☞ Detergents are effective in both hard and soft water
➥Cleansing Action of Soap
☞ Most dirt is oily in nature and hydrophobic end attaches itself with dirt and the
ionic end is surrounded with molecule of water.
☞ This result in formation of a radial structure called micelles.
☞ Soap micelles help to dissolve dirt and grease in water and cloth gets cleaned.
☞The magnesium and calcium salt present in hard water react with soap molecule to form insoluble product called scum. This scum creates difficulty in cleansing action.
☞ By use of detergent, insoluble scum is not formed with hard water and cloths get cleaned effectively.
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