1 - Review all questions 1 answers  /25

    1)          Draw the displayed formula for 3-bromo 2-methyl butanoic acid  [1]

                                    All bonds shown and carbons included

    2)           Write a balanced chemical equation for the complete combustion of ethanol  [3]

                    C₂H₅OH    +    3O₂    à    2CO₂    +    3H₂O   

                                            [1]              [1]              [1]

    3)           The cracking of decane produced hexane and one other product.

                  Write a balanced chemical equation for this reaction.  [2]

                    C₈H₁₈    à    C₆H₁₄    +    C₂H₄  

                                           [1]              [1]

    4)           Write an equation showing the initiation step for the reaction between chlorine and methane.

                  Describe the bond breaking.  [2]

                                Cl₂          à        Cl^.           +          Cl^.           UV light  [1]

                                Homolytic fission    [1]

    5)           For the reaction in (4), write out the propagation steps [2]

                                Cl^.    +    CH₄     à        HCl           +          ^.CH₃      [1]

                              ^.CH₃    +    Cl₂     à        CH₃Cl           +         Cl^.      [1]

    6)           For the reaction in (4), write out the termination steps [3]

                   Cl^.        +       Cl^.           à        Cl₂                   [1]

                   CH₃^.    +       CH₃^.       à        CH₃ – CH₃      [1]

                   Cl^.        +       CH₃^.       à        CH₃Cl          [1]

    7)          Describe the type of reagent and mechanism for questions 4 - 6   [2] 

                    Free radical  [1]  Substitution [1]

    8)          Describe a simple chemical test to distinguish between an alkane and an alkene. 

                 Include any observations. [3] 

                        Add bromine water   [1]

                        Stays orange with the alkane   [1]

                        Turns clear and colourless with the alkene   [1]

    9)          Show with the aid of curly arrows the mechanism for the reaction between chlorine and ethene [5] 

                                    Dipole on chlorine  [1]

                                    Curly arrow from middle of C=C to d+ Cl  [1]

                                    Curly arrow from middle of Cl - Cl to d- Cl  [1]

                                    Correctly drawn carbocation  [1]

                                    Curly arrow from a pair of electrons on the Cl ion to the positive carbon  [1]

    10)          Describe the type of reagent and mechanism for question 9   [2] 

                    Electrophilic  [1]  Addition [1]