Page 1 - ln1
P. 1

SAI International School

                                                       Class – VII
                                                 Subject – Chemistry

                                                Topic –Animal Fibres
              Sub-Topic –Differentiate Natural Wool & Silk Fibre from Synthetic Fibres

                                                   LESSON NOTES

        Lab. Activity:

        Aim:  Differentiate between woollen, silk & nylon fibre by performing


        flame test.


       Fibre                Behaviour              Smell                 Formation of ash
                            towards flame
       woollen              Burns readily          Smell of              Light and crushable
                            and curl away          burning hair.         beads
                            from flame
       Silk                 Burns readily          Smell of              Light and crushable
                            and curl away          burning hair.         beads
                            from flame
       Nylon/polyester  Catches fire                Smell of             Un crushable beads
                            easily as melt on      burning plastic
                            burning
       Cotton                Takes time to         Smell of              Soft and powdery ash
                            burns                  burning paper.



        Conclusion: Natural fibres (animal fibres) on burning gives smells of burning hair and
        plant fibres on burning gives smell of burning paper whereas artificial fibres on burning
        give the smell of burning plastics.





















                                                                                                                   1
   1