Experiment #3 – Synthesis of Alum
Purpose – synthesize alum which is KAl(SO ) 4 22H O a2d showing recycling
waste water treatment
lubricant in a factory between grinding metals
Very pure alum ~$3500 per gram
I. Bring an Aluminum can to lab
1) Cut a 5 cm x 7.5 cm piece from the can using scissors.
2) Clean the piece with steel wool (remove paint and plastic coating)
3) Record weight of aluminum piece. (Want about 1 g)
4) Cut the aluminum into small squares and place in 250 mL beaker.
1) Add 50 mL 1.4 M KOH (potassium hydroxide)
2) Cover beaker with a watch glass.
3) Heat gently on a hot plate under the hood.
a. Should see bubbles as hydrogen gas rises.
b. Solution should turn grey.
4) Stop when bubbles stop. (approx.. 20 minutes)
III. Assembling Hot Filtration Apparatus
1) Get a ring stand and filter flask.
2) Attach them and immobilize the flask.
3) Use filter vacuum and pour solution into filter as vacuum goes. (MUST STILL
a. It helps to stir the solution b