hydrocarbons

Question 1

alkanes aka? its hybridization, geometry, no of bonds(ethane) bond angle and bond length

Answer 1

alkanes aka paraffins, sp3 hybridization, tetrahedral geometry, 7 sigma bonds in ethane, bond angle is 109 and bond length is 1.54

Question 2

alkenes aka? its hybridization, geometry, no of bonds(ethene) bond angle and bond length

Answer 2

alkenes aka olefins, sp2 hybridization, trigonal geometry, 5 sigma and 1 pi bond in ethene, bond angle 120 and bond length 1.34

Question 3

alkynes aka? its hybridization, geometry, no of bonds (ethyne) bond angle and bond length

Answer 3

alkynes aka acetylenes, sp hybridization, linear geometry, 3 sigma and 2 pi bonds in ethyne , bond angle 180 and bond length 1.20

Question 4

benzene its hybridization, geometry, no of bonds(ethane) bond angle and bond length and m.mass

Answer 4

sp2 hybridization, trigonal geometry, 12 sigma and 3 pi bonds in benzene, bond angle 120 and bond length 1.39. molecular mass is 78

Question 5

preparation of alkenes (ethene)

Answer 5

1) Dehydration of alcohol (in presence of h2so4)
2) Dehydrohalogenation of alkyl halide (reaction w KOH)

Question 6

preparation of alkyne (ethyne)

Answer 6

1)Dehydrohalogenation of vicinal dihalide
2)Dehalogenation of tetrahalide

Question 7

reactions in alkenes/ what type and how many type of reactions?

Answer 7

addition reactions occur in alkenes 6 types
1) Hydration (+ water)
presence of acid catalyst (h2so4)
results in alcohol

2) Hydrogenation (+ hydrogen)
in presence of metal catalyst pt,pd,ni etc
results in ethane

3) Halogenation (+ halogen Br2, Cl2 or I2)
results in dihaloalkanes

4)hydrohalogenation (+ H and X)
results in alkyl halide

5) Halo hydration (+ h2o and X)
results in halohydrin

6) Epoxidation (+ oxygen)
results in epoxide

Question 8

ozonolysis in alkenes and alkynes

Answer 8

IN ALKENE:
cleavage of alkene by addition of ozone (O3). in presence of zinc. results in ozonide intermediate which then forms aldehyde

IN ALKYNE:
cleavage of alkyne by addition of ozone (o3). results in ozonide intermediate which then become glyoxal

Question 9

reactions in alkynes/ what type and how many type of reactions?

Answer 9

addition reactions occur in alkynes.
5 types

1)hydrogenation (add hydrogen)
*in presence of metal catalyst like pt pd ni etc)
results in alkene and then alkane

2) hydrohalogenation (+ H and X)
results in dihaloalkane

3) hydration (+water)
in presence of h2so4
results in enol (vinyl alcohol) which rearrange to form aldehyde or ketone.

4)bromination (+ Br2)
results in di bromo ethene and then tetrabromo ethane

Question 10

addition reactions in benzene

Answer 10

addition and substitution reaction occur in benzene
ADDITION REACTIONS:
1. addition of hydrogen
in presence of Ni catalyst
results in cyclohexane
2. addition of halogen (CL2 or Br2)
in presence of UV light
results in hexahalocyclohexane

Question 11

substitution reactions in benzene and its types

Answer 11

electrophile substitution of benzene:
involves the replacement of weak electrophile with a strong electrophile.
types of E.S.R (5 types)
1. Nitration
addition of HNO3 (nitric acid)
in presence of h2so4
results in nitrobenzene

2. sulphonation
   addition of sulphuric acid
   results in benzene sulphonic acid
3. halogenation
   addition of halogen
   *in presence of lewis acid(fECL2)
   results in halobenzene
4. friedal craft alkylation
   addition of alkyl halide in benzene
   *in presence of lewis acid (Alcl3)
   results in alkyl benzene
5. friedal craft acylation
   addition of acyl halide in benzene
   *in presence of lewis acid (Alcl3)
   results in arylketone

Question 12

reason for acidic nature of alkynes

Answer 12

due to 50% s character from sp hybridization.

Question 13

isomerism and name its types

Answer 13

isomerism is ability of a compound to form isomers. isomers are the compounds with same molecular formula but diff structural formula OR isomers have same number of atoms but diff arrangement of atoms.
2 types
structural isomers and stereo isomers

Question 14

structural isomers

Answer 14

compounds w same no of atoms but different arrangement of those atom.
4 types
1. chain isomerism
change in the main chain
2. position isomer
change in position of functional group
3. functional grp isomer
change in the functional group
4.metamerism
change in distribution of atom on either side of functional grp.

Question 15

stereoisomers define only

Answer 15

compounds with same molecular formula but different 3d structure.

Question 16

type of stereo isomers

Answer 16

2 types
1) optical isomers
compounds with molecular formula but are mirror image of each other.
present in chiral compounds
aka enantiomers.
they show diff behavior in light (bend light in left or right)
if they bend light left they are cld levorotatory and if they bend light in right they cld dextrorotatory

2) geometrical isomers
compounds with same molecular formula but diff arrangement of atoms in relation to each other.
present in double bonded compound w diff groups or cyclic compounds
if the group of compound is on same side its cld cis isomer and if group on opposite side its cld trans isomer.

Question 17

electrophile attacks on benzene so what happens

Answer 17

1. carbo cation forms known as arenium ion.
2. bond rotation occur which is known is sigma complex
3. benzene loses its aromaticity

Question 18

friedal craft acylation results in which type of product?

Answer 18

aromatic ketone