Heep Woh College

Form 5 Chemistry Quiz 5

Chapter 23 : Organic Chemistry

Marking Scheme

 

1.     (a) Explain the meaning of the term “homologous series”. Use the alkanol

homologous series as your example.                                                                   [3]

 

                Organic compound with the same functional group: -OH                          1

Same general formula: C_nH_2n+1OH / C_nH_2n+2O                                                  1

Each successive members differ by one -CH₂- unit. E.g. CH₃CH₂OH, CH₃CH₂CH₂OH                                                                                                            1

 

 

 

        (b)  Suggest ONE similarity and ONE difference between members in alkanol.

[2]

Similarity:    similar chemical reaction / chemical properties.                    1

               Difference:  gradual change of physical properties, e.g. melting point.  1

                                      (Not accept different physical properties)

 

 

 

2.    Give the name in IUPAC for the following compounds.                                             [5]

 

(a)  (CH₃)₃CCHF₂                                    1,1-difluoro-2,2-dimethylpropane          1

 

(b)  ClCBr₂CH₂CH₂CH₂I                        1,1-dibromo-1-chloro-4-iodobutane     1

 

        (c)  (CH₃)₃CCOOH                                2,2-dimethylpropanoic acid                    1

 

        (d)  CH₂=CHCH=CH₂                            buta-1,3-diene                                              1

 

        (e)  CH₃CH=CHCH₂OH                        but-2-en-1-ol                                                 1

 

3.    Draw the structural formulae for the following compounds.                                     [4]

        (a)  1,1,1-triiodopropane                            (b)  butane-1,4-dioic acid

	I   H   H    |   |   | I¾C¾C¾C¾H    |   |   |    I   H   H		O   H  H  O        ||    |   |  || HO¾C¾C¾C¾C¾OH             |    |           H   H

 

 

 

 

 

 

                                                                                                                                                      1,1

 

 

 

 

 

        (c)  2,2,3,3-tetrachlorobutan-1-ol            (d)  octabromopropane

	H   Cl  Cl  H         |    |   |   | HO¾C¾C¾C¾C¾H        |    |   |   |      H   Cl  Cl  H		Br  Br  Br      |   |   | Br¾C¾C¾C¾Br      |   |   |     Br  Br  Br

 

 

 

 

 

 

                                                                                                                                                      1,1

 

4.    (a)  What is structural isomers?                                                                                     [2]

 

Compounds with the same molecular formula                                                      1

but different structural formulae                                                                                    1

 

 

(b)  Draw and name with IUPAC for any THREE possible structural isomers of C₄H₁₀O.                                                                                                                    [6]

 

               CH₃CH₂CH₂CH₂OH          butan-1-ol

 

               CH₃CH₂CH(OH)CH₃         butan-2-ol

              

               (CH₃)₃COH                        methylpropan-2-ol

 

               (CH₃)₂CHCH₂OH              methylpropan-1-ol        (ANY THREE PAIRS)

 

               (Accept other possible answers. E.g. compounds with ¾O¾)    

 

               Each correct name: 1 mark; each correct structural formula: 1 mark.     6

 

       

 

 

 

The End