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, , The branch of chemistry which deals with hydrocarbons and their, derivatives is called organic chemistry., , , , Carbon forms large number of organic compound because of its properties, of catention and tetravalency., , , , Functional Group : An atom or a group of atoms joined in a speci®c, manner, which provides certain characteristics chemical properties to the, organic compounds, is called functional group., , , , Homologues : A group or series of an organic compound each containing a, characteristics functional group from a homologous series and the members, of the series are called “homologues”., , , , Fission of a Covalent Bond :, (a) Homolytic cleavage : In this cleavaage, one of the electrons of the, shared pair in a covalent bond goes with each of the bonded atoms., , www.tiwariacademy.com, (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in, such a fashion that the shared pair of electrons remains with one of, the fragment., , , , Electron Displacement Effects in Bovalent Bonds., Inductive effect (I) : Polarisation of a bond caused by the polarisation of, adjacent bond is referred to as the inductive effect., The p-Block Elements, , 113

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+ Inductive effect (+ I), Two types of inductive effect, – Inductive effect (– I), , , , It is a permanent effect and decrease with the increase in distance., – I effect : —NO2 > —F > —Cl > —Br > —I > —OCH3 > – C6H5, + I effect : —C(CH3)3 > — CH(CH3)2 > —C2H5 > —CH3, , , , Electromeric effect : The complete transfer of the shared pair of , electrons of a multiple bound to one of the atoms in the presence of the, attracking reagen is called electromeric effect., , , , If the transference of e– towards attacking reagent + E effect., , , , If the transference of e– takes place away from attacking reagent – E effect., , , , Resonance effect (+ R effect) : The polarity produced in the molecule, by the interaction of two -bond and lone pair of electrons present on an, adjacent atom., , , , Hyper conjugation : It is special kind of resonance in which delocalisation, of e– takes place through overlap between -bond orbital and -orbital., It is also called no bond resonance., , 114, , Chemistry Class XI

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, , IUPAC Nomenclature of Organic Compounds : Following rules are, used to write the IUPAC name of an organic compound., Rule 1., , , , Longest chain rule : The chain containing the principal functional group,, secondary functional group and multiple bonds as many as possible is the, longest possible chain., In the absence of functional group, secondary group and multiple bonds,, the chain containing the maximum number of C-atoms will be the longest, possible chain e.g.,, , Choose the word root from the table given below for the longest possible, chain., , Word Root for Carbon Chain, Chain length, , Word root, , Chain length, , Word root, , C1, , Meth-, , C7, , Hept, , C2, , Eth-, , C8, , Oct, , C3, , Prop-, , C9, , Non, , C4, , But-, , C10, , Dec, , C5, , Pent-, , C11, , Undec, , C6, , Hex-, , C12, , Dodec, , The p-Block Elements, , 115

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Percentage of nitrogen :, =, , , Estimation of halogens : (Carius method) :, Percentage of chlorine =, Percentage of bromine =, Percentage of iodine =, , , , , Percentage of sulphur =, Estimation of phosphorus : A known mass of the organic compound, is heated with fuming HNO3 in a Carius tuble when phosphorus of the, organic compound is oxidized to H3PO4. Phosphoric acid thus formed is, precipitated as magnesium ammonium phosphate by adding magnesia, mixture (a solution containing MgCl2, NH4Cl and NH4OH.), Percentage of phosphorus :, , , , Estimation of oxygen : A de®nite mass of an organic compound is, decomposed by heating with N2 gas. The mixture is then passed over red, hot coke when all oxygen is converted to CO. This mixture is then passed, through I2O5 when CO is oxidised to CO2 producing iodine. The % of, oxygen can be derived from the amount of CO2 or I2 produced., Percentage of oxygen :, , Method of Purification of organic compounds :, , , Crystallisation : Process of solidi®cation of a pure substance from its, dissolved state. This method is based upon differences in their solubility, in a given solvent or in mixture of solvents., , 120, , Chemistry Class XI

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, , Sublimation : It is a process of conversion of a solid into gaseous state, on heating without interchaning into liquid. The process is used for the, separation of volatile solids, which subline on heating from the non-volatile, solids., , , , Distillation : It is a process of conversion of a liquid into vapours by, heating followed by condensation of vapours. The method is used for the, puri®cation of liquids which boil without decomposition and are present, with non-volatile impurities., , , , Fractional distillation : Process used to separate mixture of two or, more miscible liquids having different boiling points. It is mainly used in, distillation of petroleum, coaltar and crude alcohol., , , , Distillation under reduced pressure : This process is used when the, liquid has a tendency to decompose near its boiling point. Under reduced, pressure, the liquid will boil at a low temperature without decomposing., , , , Steam distillation : Purification of a substance from non-volatile, impurities provided the substance itself is volatile in steam and insoluble, in water., , , , Chromatography : Technique of separating the consitituents of a, mixture by the differential movement of individual components through, the stationary phase under the in¯uence of mobile phase. Two types of, chromatography., Chromatography, Adsorption Chromatography, , Column, , Thin layer (TLC), , Partition Chromatography, Paper chromatography, , The p-Block Elements, , 121

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1-Mark Questions, , Some Basic Concepts of Organic Chemistry, 1. Identify the most electronegative element in CH2FCl., 2. Write the hybrid orbitals used by 'C' in ethene ., 3. Identi®y the tertiary (3°) and quarternary (4°) carbon in, , 4. How many  and  bonds are there in, 5. What is the functional group of (i) an aldehyde (ii) a nitro compound ?, 122, , Chemistry Class XI

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2-Mark Questions, 6. How many  and  bonds are present in each of the following, , molecules ?, (a) HC  CCH = CHCH3 (b) CH2 = C = CH—CH2CH3, [Ans. (a) = 10,  = 3 (b)  = 12,  = 2], 7. Mention the hybridisation of C* and shape of the compound., , (a) H2C* = O (b) CH3—C*  N, 8. Which bond in more polar in the following pair of molecules :, , (a) CH3—H or CH3—Br (b) CH3—NH3 or CH3—OH, 9. Draw formula of ®rst four members of homologeous series begining with, the compound CH2 = CH2., 10. (a) Why does carbon exhibit catenation to maximum extent ?, , (b) Give hybridization of each carbon in following compound, CH2=CH—CN., 1-Mark Questions, , Nomenclature, 1. Write the IUPAC name of, , (a), , (b), , 2. Draw structure of 3-isopropyl-2-methylhexane., 3. Write the structure of compound that contains both 1° and 2° alcohol., 4. Give IUPAC name of following :, , (a), , The p-Block Elements, , 123

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(b), , 5. Give IUPAC name of following bond-line formulae :, , (a), , (b), , 2-Mark Questions, 6. Write the correct order of priority of the following functional groups :, , —CN,, , , —OH,, , 7. Write the structural formula of :, , (i) O-Ethylanisole, , (b) 4-ethyl-1-¯uoro-2-nitrobenzene, , 8. Identify the functional groups in :, , (a), , (b), , 9. Give IUPAC name of following :, , (a) CH3 — (CH2)3 — CH — CH (CH3) — CH (CH3)2, |, CH2 — CH2 — CH (CH3)2, (b), , 10. Give condensed and bond-line structural formulae and identify the, , functional group(s) present, if any for :, (a) Cyclo octa-1, 5-dine, (b) 2(4-isobutylphenyl) propanoic acid, 124, , Chemistry Class XI

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3-Mark Questions, 11. Draw the structure of :, , (a) Pent-3-enoic acid, (b) 4-Methylpentanone, (c) 4-Ethyl-3-¯uorophenol., 12. Write the IUPAC name of the following compound :, , 1 Mark Questions, , Isomerism, 1. Write functional isomer of molecular formula C 3H6O., 2. Write tautomeric form of following structures :, , (b), , (a), , 3. Identify the chiral carbon in the given compound CH3—CHOH—CH2—, CH3., , 2 Mark Questions, 4. What is the relationship between the members of the following pairs of, , structures ?, , 5. Write all the possible isomers of the aromatic compound C 8H10., , 1 Mark Questions, , Concepts in Reaction Mechanism, 1. Identify electrophilic centre in CH3CHO., 2. Identify nucleophilic centre in CH 3Br., The p-Block Elements, , 125

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3. Arrange the following in decreasing order of stability :, 4. Which species can act as an acid and why ?, , CH3—O– or CH3—OH, 5. What types of attacking reagents are produced by heterolytic cleavage of, , bonds ?, 6. Out of CH3COOH and NO2CH2COOH which is more acidic in nature, , and why ?, , 7. Identify the most stable carbonation among the following :, , ,, 8. Identify the weakest nucleophile among the following :, , , –, , –, , N H 2 ,CH3 — N — CH3 ,CH 3 — N H, 9. Select the nucleophile and electrophile in the following :, , 10. Give reason (CH3)3C+ is more stable than, , 2 Mark Questions, 11. Mark the electrophillic centre in the following molecules :, , CH3CN, CH3I, CH3CHO, CH3CH2OH, 12. Benzyllic free radical is more stable than allylic free radical. Explain with, , resonance., 13. Classify each of the following carbon intermediates :, , (a) (CH3)3C, , (b), , (c), , (d), , 14. Classify whether the following reaction is rearrangement addition, or, , elimination ?, , 126, , Chemistry Class XI

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15. Write the product of following reaction., , (1), (2) CH3CH2CH2CH3, 5 Mark Questions, 16. Write structure of various carbocation that can be obtained from, , 2-methylbutane. Arrange thee carbocation in order of increasing stability., 17. Classify the reaction type as elimination, rearrangement addition and, , substitution., (a), , (b), , (c) CH3—CH(Br)—CH(CH3)2, 18. Follow the ¯ow of electrons indicated by the curved arrows and predict, , the products :, (a), , (b), , (c), , The p-Block Elements, , 127

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19. Name the electrophile/nucleophile generated by following species :, , (a) HNO3 + H2SO4, (c) alc. KCN, , (b) CH3COCl, , 20. Identify the nucleophiles, electrophiles and free radicals amongst the, , following :, Cl+, BF3, (CH3)3N,, , ,, , 21. Which is more stable and why ?, , (a), , (b), , (c), 5 Mark Questions, 1. Arrange the following according to given property :, , (dereasing order of stablity), 2., , –, , –, , –, , –, , HC  C, CH 2  C H, CH 3 – C H 2 , C H 3 (increasing order of stability), , 3., , (increasing order of stability), , 4., , (dereasing order of stablity), (decreasing order of, stablity), , 5., , 2-Mark Questions, , Electronic Displacement in Covalent Bond, 1. Name the kind of effect that operates to explain the stability of carbocations., 2. Why inductive effect is also called transmission effect ?, 128, , Chemistry Class XI

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3. Which permanent effect of organic compound is also known as ‘No bond, , resonance effect’ ?, 4. Which is correct and why ?, , 5. Write resonating structure of the following and show the movement of, , electron by curved arrows :, (a) CH3—COO–, , (b) CH2 = CH—Cl, 2 Mark Questions, , 6. Draw the resonating structure of :, , (a), , (b), , 7. Write resonance structure of :, , (a) C6H5NH2, , (b) C6H5NO2, , 8. Explain why alkyl groups acts as e– donar when attached to a -system., 9. Resonance structures of propenal are given below. Which of these, , resonating structure is more stable ? Give reason., CH2 = CH—CH = O, (I), , (II), , 10. Explain the following terms :, , (a) Electromeric effect, (b) Hyperconjugation, 11. (a) Explain + I and – I effect., (b) Select the group giving + I effect and – I effect from the following, list :, (i) —NO2 (ii) —CN (iii) Cl– (d) CH3–, 12. Explain the importance of inductive effect in determination of acidic or, basic strength of substances., 13. Write resonance structure of CH2= CH—CHO. Indicate relative stability, of the contributing structures., 5-Mark Questions, 1. Give reason for the following :, (a) Chlorobenzene is o– and p– directing towards the electrophillic, substitution reaction., (b) Inductive effect decrease with the increase in distance., (c) Hyperconjugation effect is extended form of resonance effect., The p-Block Elements, , 129

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2. Arrange the following according to given property :, , (a) —NO2, —COOH, —F, —CN, —I (increasing order of – I effect), (b) CH3—, (CH3)2C—, (CH3)2CH—, CH3CH2—, (decreasing order of + I effect), , Purification Methods, 1 Mark Questions, 1. What conditions must be satis®ed by a suitable solvent in the crystallization, , method ?, 2. Which technique can be used for puri®cation of iodine that contains traces, , of NaCl ?, 3. When do we use hot water funnel for ®lteration ?, , [Hint : When organic substance crystallises during ®ltration.], 4. A liquid (10 mL) has three components A, B, C. Which technique is most, , suitable to separate A, B, C from such a small amount of mixture ?, 5. A substance has boiling point 355 K, but it starts decomposing near this, , temp. Which type of distillation process is suitable for its puri®cation ?, 6. Name the adsorbent used in column chromatography., 7. Which technique can be used to seperate napthlene from kerosene oil, , present in its mixture ?, 8. A mixture contains nitrobenzene and benzoic acid. How can this mixture be, , separated into its constituents by technique of extraction using appropriate, chemical reagent ?, [Hint : By using hot water as solvent and adopting differential extraction.], 2 Mark Questions, 9. The Rf value of A and B in a mixture determined by TLC in a solvent, , mixture are 0.65 and 0.42 respectively. If the mixture is separated by, column chromatography using the same solvent mixture as a mobile phase,, which of the two components A or B will elute ®rst ? Explain., [Hint : A will elute ®rst because it has more Rf value.], , 10. Name a suitable technique of separation of the components from a mixture, , of :, (a) Water and aniline., (b) Methanol and Propanone., 130, , Chemistry Class XI

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Qualitative and Quantitative Analysis, 2-Mark Questions, 1. A student was given the compound C 6H4(NH2)SO 3H for elemental, , analysis, while performing Lassaigne’s test for N, what colour will he get, and why ?, , 2. Why diazonium salts do not show sodalime test for nitrogen ?, , [Hint : Because salts do not liberate NH3 gas under there conditions.], 3. What is the function of fusing the organic compound with sodium, , metal ?, 4. If silver nitrate solution is added to chlorobenzene, will there be formation, , of white ppt., 5. Name the oxidising agent used in the combustion tube along with the, , organic compound., , [Ans. CuO], 2-Mark Questions, , 6. Why is it necessary to boil Lassaigne’s extract with HNO3 before testing, , it for halogens ?, , 7. 0.25 g of an organic compound containing C, H and O was analysed by, , the combustion method. The increase in the man of calcium chloride tube, and the potash bulbs at the end of the operation was found to be 0.15 g, and 0.1837 g respectively. Calculate the percentage composition of the, compound., 8. Will CCl4 give white precipitate of AgCl on heating it will silver nitrate, , ? Give reason., , 9. For which type of compounds Kjeldahl’s method is not applicable ?, 10. 0.90 of an organic compound on combustion 2.64 g of CO2 and 0.63 g of, , H2O. Calculate the percentage of C and H in the compound., , 3-Mark Questions, 11. What will happens if a student acidi®es the Lassaigne's extract with dil., H2SO4 in place of dilute HNO3. Write the reaction involved., 12. (a) In DNA and RNA, nitrogen atom is present in the ring system. Can, , Kjeldahl’s method is used for the estimation of N-present in these. Give, reasons., (b) Why is it necessary to use ethanoic acid and not sulphuric acid for, The p-Block Elements, , 131

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acidi®cation of sodium extract for testing sulphur by lead acetate test ?, 13. 0.2325 g of an organic compound was analysed for nitrogen by Duma’s, method. 0.0317 L of moist nitrogen was collected at 25°C and 755.8 mm, , pressure calculate the percentate of nitrogen., [Ans. Aq. tension of water at 25°C is 23.8 mm Hg], 5-Mark Questions, 14. (a) Out of the different gases formed in Duma’s method, which gas is not, , observed over an aqueous solution of KOH., (b) What is the function of adding small amount of K2SO4 and a little, amount of Hg or CuSO4 is Kjeldahl's ¯ask ?, (c) Explain why a solution of KOH used to absorb CO2 evolved during, the estimation of carbon in an organic compound., (d) An organic compound contain diazo group (—N=N—) or nitro, group or ‘N’ in the ring. Name the method used to estimate nitrogen, in the compound., (e) In victor Meyer’s method, what is the gas collected in the gas jar ?, [Hint : Oxygen gas], 15. (a) 0.4 g of the compound was Kjeldahl’s and ammonia evolved was, , absorbed into 50 ml of, , H2SO4 solution. The residual acid solution, , was diluted with distilled water and the volume was made upto 150 ml., 20 ml of this diluted solution required 31 ml of, , NaOH solution for, , complete neutratization. Calculate the % of N is compound.[Ans. 46.8%], (b) Write the formula for the prursian blue colour obtained during, Lassaigne’s test for nitrogen., (c) Give test to detect the presence of sulphur in compound., , 132, , Chemistry Class XI