How will you demonstrate that double bonds of benzene are somewhat different from that of olefins?

1 Answer

Answer :

Ans. The double bonds of olefins decolorize bromine water and discharge the pink colour of Bayer‘s reagent while those of benzene not.

Related questions

Description : Explain the physical properties of benzene and its homologues.

Last Answer : Ans: i. Benzene and its homologous upto eight carbon atoms are colourless liquids with characteristic smell. ii. Aromatic hydrocarbons are immiscible with water but soluble in organic solvents. iii. ... compounds increases with increase in molecular mass due to increase in van der waals forces.

Description : Out of benzene, m–dinitrobenzene and toluene which will undergo nitration most easily and why?

Last Answer : Ans. -CH3 group is electron donating while –NO2 group is electron withdrawing. Therefore, maximum electron density will be in toluene , followed by benzene and at least in m-dinitrobenzene. Therefore, the ease of nitration decreases in the order: Toluene> benzene> m-dinitrobenzene

Description : Which one is more stable structure of benzene among Kekule and Dewar’s structures?

Last Answer : Ans: Kekule’s structure.

Description : Why do the C-C bonds rather than C-H bonds break during cracking of alkanes?

Last Answer : Ans. Since the bond dissociation energy of C-C bonds (348kj /mol) is lower than bond dissociation energy of C-H bonds (414kj/mol), therefore, during cracking of alkanes, C-C bonds break more early than C-H bonds.

Description : What is meant by restricted rotation around of carbon-carbon double bond? What type of isomerism does it lead to?

Last Answer : Ans. The carbon-carbon double bond in alkene contains one sigma bond and one pi-bond. The Pibond involves the overlapping of unhybridised p orbital of two carbon atom .The rotation around the ... , the free rotation around C=C double bond is restricted, which gives rise to Geometrical Isomerism.

Description : Define benzenoids Compounds.

Last Answer : Ans: Aromatic compounds containing benzene ring.

Description : Define Aromatic Compounds.

Last Answer : Ans: The Compounds which gives pleasant smell.

Description : What are alkanes? Why are they called paraffins?

Last Answer : Ans. Those hydrocarbons which contain single bond between carbon- carbon are called alkanes. They are called paraffins because they are very less reactive (Latin- Parum= little, affins = affinity)

Description : How will you separate propene from propyne?

Last Answer : Ans. By passing the mixture through ammonical silver nitrate solution when propyne reacts while propene passes over.

Description : What is Grignard reagent?

Last Answer : Ans. Alkyl magnesium halides

Description : How will you detect the presence of unsaturation in an organic compound?

Last Answer : Ans. Generally Unsaturated organic compound decolorize Bayer‘s reagent and Bromine water.

Description : Arrange the following in order of decreasing reactivity towards alkanes. HCl, HBr, HI, HF

Last Answer : Ans. HI> HBr> HCl >HF

Description : Name two reagents which can be used to distinguish between ethene and ethyne.

Last Answer : Ans. Tollen‘s reagent

Description : Out of ethylene and acetylene which is more acidic and why?

Last Answer : Ans. Acetylene, due to greater electonegativity of the sp hybridised carbon.

Description : Arrange the following in the increasing order of C-C bond length- C2H6 , C2H4, C2H2

Last Answer : Ans. C2H2 < C2H4 < C2H6

Description : What effect does branching of an alkane chain has on its boiling point?

Last Answer : Ans. As branching increases, the surface area of the molecule decreases which results in a small area of contact. As a result, the Van der Waals force also decreases which can be overcome at ... lower temperature. Hence, the boiling point of an alkane chain decreases with an increase in branching.

Description : What are the necessary conditions for any system to be aromatic?

Last Answer : Ans. A compound is said to be aromatic if it satisfies the following three conditions: (i) It should have a planar structure. (ii) The π-electrons of the compound are completely delocalized in the ring. (iii)The total number ... to (4n + 2), where n = 0, 1, 2 etc. This is known as Huckel s rule.

Description : Explain why Grignard reagents do not reacts with alkanes.

Last Answer : Ans. In alkanes , the C – H bond has very little polarity . The hydrogen cannot be abstracted by the Grignard reagent.

Description : What are the main constituent of LPG?

Last Answer : Ans. Butane and isobutane . Both these isomers can be easily liquified and hence can be conveniently transported in iron cylinder.

Description : Is it possible to isolate pure staggered ethane or pure eclipsed ethane at room temperature? Explain .

Last Answer : The energy differences between staggered and eclipsed forms of ethane is just 12.55 kj mol_1 which is easily met by collisions of the molecules at room temperature. Therefore, it is not possible to isolate either pure staggered or pure eclipsed ethane at room temperature.

Description : Which of the following has highest boiling point and why?(L-II) (a) 2 methylpentane (b) 2,3 dimethyl butane (c) 2,2 dimythylbutane

Last Answer : Ans. As the branching increases, surface area decreases. As a result, magnitude of Vander Waals forces of attraction decreases and hence the boiling point decreases. Thus, the overall order of decreasing boiling point is: 2 methylpentane (333k) > 2,3 dimethylbutane (331k) > 2,2 dimethylbutane(323k)

Description : (a) What effect the branching of an alkane has on its melting point? (L-III) (b) Which of the following has highest boiling point?(L-III) (1) 2-methyl pentane. (2) 2, 3-diethyl butane. (3) 2, 2- dimethyl butane.

Last Answer : Ans.(a) In general conception, as the branching increases packing of the molecules in the crystals becomes less close and have melting point decreases accordingly. (b) As the branching increases, ... attraction decreases and hence the boiling point decreases. So, 2-methyl pentane has highest B.pt.

Description : Arrange the three isomers of pentane in increasing order of their boiling points?

Last Answer : Ans.2, 2-Dimethylpropane

Description : What do you mean by pyrolysis?

Last Answer : The decomposition of a compound by the heat is called pyrolysis. This process when applied to alkanes is known as cracking.

Description : Why are alkanes called paraffins?

Last Answer : Paraffin’s means little affinity; alkanes due to strong C-C and C-H bonds are relatively chemically inert.

Description : What are conformations?

Last Answer : Conformations are spatial arrangements which are obtained by rotation around sigma bonds.

Description : Benzene undergoes substitution reaction more easily than addition reaction because (a) it has a cyclic structure (b) it has three double bonds (c) it has six hydrogen atoms (d) there is delocalization of electrons

Last Answer : there is delocalization of electrons

Description : Benzene undergoes substitution reaction more easily than addition reaction because (a) it has a cyclic structure (b) it has three double bonds (c) it has six hydrogen atoms (d) there is delocalization of electrons

Last Answer : there is delocalization of electrons

Description : Which statement about the structure of benzene is not true? (a) The two Kekule structures of benzene are in equilibrium. (b) The carbon-carbon bond lengths in benzene are greater than the carbon- ... (d) The stability of benzene ring is much greater than the stability of 1,3,5- cycloheptatriene

Last Answer : The two Kekule structures of benzene are in equilibrium

Description : Which of the following statements are correct concerning benzene? (a) Benzene is a planar molecule. (b) The six carbon-carbon bonds have the same length. (c) Benzene has alternating single and double bonds. (d) (a) and (b)

Last Answer : (a) and (b)

Description : Which of the following reactions of benzene proves the presence of three carbon-carbon double bonds in it :

Last Answer : Which of the following reactions of benzene proves the presence of three carbon-carbon double ... of concentrated nitric acid and sulphuric acid

Description : An organic compound (A) has a molecular weight 78 and an empirical formula CH. (A) is resistant to attack by oxidizing agents but undergoes substitution and addition reactions. X-ray analysis shows that the ... suggests that compound (A) is (a) Benzene (b) Cyclohexane (c) Toluene (d) n-Hexane

Last Answer : Benzene

Description : An organic compound (A) has a molecular weight 78 and an empirical formula CH. (A) is resistant to attack by oxidizing agents but undergoes substitution and addition reactions. X-ray analysis shows that the ... suggests that compound (A) is (a) Benzene (b) Cyclohexane (c) Toluene (d) n-Hexane

Last Answer : Benzene

Description : What is Alkyne or Olefins ?

Last Answer : Hydrocarbons that have two carbon atoms joined together by a double bond in a carbon chain are called alkynes or olefins.

Description : Compounds of carbon having double or triple bonds between their carbon atoms are called (1) Saturated compounds (2) Unsaturated compounds (3) Reactive compounds (4) None of the above

Last Answer : (2) Unsaturated compounds Explanation: Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds. Compounds of carbon having double or triple bonds between their carbon atoms are called unsaturated compounds.

Description : Who do double bonds in rubber molecules influence there structure and reactivity.

Last Answer : Ans: Greater the number of double bound the rubber will be less reactive because of greater inter molecular forces of attraction among the monomers.

Description : How do double bonds in the rubber molecule influence their structure and reactivity ?

Last Answer : Due to presence of double bond the rubber molecule show cis-configuration because which the polymer chains can not come close to each other and get boiled but as they have their ... Waals intraction between the molecules consequently they get elastic property, solubility in organic solvents etc.

Description : The double helical structure of DNA is held together by (a) sulfur-sulfur linkages (b) peptide bonding (c) hydrogen bonding (d) glycosidic bonds

Last Answer : hydrogen bonding

Description : Which of the following statements is not true about fatty acids? (a) Fatty acids are carboxylic acids with long hydrocarbon side chains. (b) The double bonds in unsaturated fatty acids are always ... contain even numbers of carbons and are unbranched. (d) Fatty acids can be saturated or unsaturated

Last Answer : The double bonds in unsaturated fatty acids are always conjugated

Description : Liquid oils can be converted to solid fats by (a) Hydrogenation (b) Saponification (c) Hydrolysis (d) Oxidation of double bonds

Last Answer : Hydrogenation

Description : Which brief statement most accurately describes why alkenes react the way they do? (a) C=C double bonds are weak. (b) A π bond is lost but a stronger σ bond is gained. (c) C=C double bonds are unstable. (d) C=C π bonds are attacked by nucleophiles.

Last Answer : A π bond is lost but a stronger σ bond is gained.

Description : Which of the following molecular formulas will correspond to an alkene with two double bonds? (a) C4H10 (b) C5H12 (c) C6H10 (d) C8H16

Last Answer : C6H10

Description : Carbon-carbon double bonds consist of : (a) one σ bond, one π bond (b) two σ bonds, one π bond (c) one σ bond, two π bonds (d) two σ bonds, two π bonds

Last Answer : one σ bond, one π bond

Description : Catenation is a property of the carbon atom which describes its ability to (a) bond with other carbon atoms (b) form double and triple bonds (c) exist in plant and animal form (d) form bonds in its ground state

Last Answer : bond with other carbon atoms

Description : What are alkenes having two double bonds separated by one single bond known as?

Last Answer : ANSWER: CONJUGATED DIENES 

Description : In 2-butene, which of the following bonds prevents the atoms at each end of the bond from rotating with respect to each other. Is it an: w) ionic bond x) sigma bond y) strong bond z) double bond

Last Answer : ANSWER: Z -- DOUBLE BOND

Description : Classify the following compounds containing double bond and triple bond – Ethyne, benzene, Butyne, pentene

Last Answer : Double bond: Benzene, pentene Triple bond: Ethyne, Butyne

Description : The bond most likely to be formed when two atoms differ SOMEWHAT in their tendency to attract electrons is: w) nonpolar ionic x) polar ionic y) polar covalent z) nonpolar covalent

Last Answer : ANSWER: Y -- POLAR COVALENT

Description : Before 1857, developments in Delhi were somewhat different from those in other colonial cities. How? -History

Last Answer : In Presidency cities, Bombay, Madras and Calcutta, the living spaces of Indians and the British were sharply separated. Indians lived in the black' areas, while the British lived in well laid ... City. The British learned to enjoy Urdu/Persian culture and poetry and took part in local festivals.

Description : What is the difference between paraffins and olefins?

Last Answer : Need answer