Tuesday 17th of september: method and materials
Potash alum, Hot water, Filter paper, Filter funnel and Beakers
Make sure all apparatus is
clean and dry.
Place approximately 25 g of
potash alum in a beaker (250 ml or bigger) and add approximately 170 ml of hot
water. Stir the mixture until all the crystals have dissolved.
(NOTE: don’t use all the alum
you have been given – keep a few crystals back in reserve in case you need to
“seed” the solution later.)
Filter the warm solution
through a filter funnel (in which filter paper has been inserted) into another
clean beaker. Cover the beaker of solution with the watch glass or fresh filter
paper and set aside in a cool sheltered place and allow it to stand undisturbed
overnight. The first beaker and funnel can be washed and dried and the residue
and filter paper used for filtration discarded.