Heep Woh College

Form 5 Chemistry Quiz 10

Chapter 27 : Plastics

Marking Schemes

 

1.    (a)  A:   Ethanol                                                            B:    Methanal

               C:   But-2-ene                                                 D:    Urea                     ½ each        ½x4

 

        (b)  (i)    Poly(but-2-ene)                                             (ii)   Urea methanal                       1x2

 

        (c)  (i)                                                                       (ii)

 

 

 

                                                                                                                                                      1x2

 

 

        (d)  (i)    Addition                                                  (ii)   Condensation                               ½x2

 

        (e)  (i)    Plastic bag, plastic bottle, …… similar to polythene                                     1

               (ii)   Socket, electrical plug……                                                                             1

 

2.    (a)

                                                                                                                       

               1 mark for the correct repeating unit of polythene,

1 mark for equation                                                                                                 2

 

        (b)  Plastics can be softened on heating, hardened on cooling.                      1

               This process can be repeated for many times.                                                1

 

        (c)  No cross-link between its molecules.                                                                   1

        OR  Only weak intermolecular forces / van der Waals’ forces                           (1)

between molecules

 

3.    (a)  Burning / combustion will happen instead of cracking.                               1

 

(b)  Adv.:     1)    useful products can be obtained

                       2)    causes less air pollution problems

                       3)    save materials

                       4)    not necessary to separate the plastic wastes                          1

 

        Disadv.:1)    high operation cost

                       2)    high cost of building plant                                                              1

 

(c)  Incineration / landfilling / recycling

(not accept burning / reuse / bury in ground)                                                1

 

(d)  Incineration

        Adv.:     1)    Low operation cost       

                       2)    Reduce solid waste volume / reduce land wastage

                       3)    Not necessary to separate the plastic wastes                         1

        Disadv.:1)    Cause air pollution                                                                             1

 

        Landfilling

        Adv.:     1)    Low operation cost       

                       2)    Causes less air pollution problems

                       3)    Not necessary to separate the plastic wastes                         1

        Disadv.:1)    Waste land        (Not accept land pollution)                             1

 

        Recycling

        Adv.:     1)    Save materials 

                       2)    Reduce solid waste volume / reduce land wastage

                       3)    Causes less air pollution problems                                                 1

        Disadv.:1)    High operation cost                                                                          1

 

 

The End