To investigate the effect of pH on the rate of catalane activity Teacher Notes Apparatus required per class group of 24 students Chopping board 12 Knife Weigh boats 100 ml Graduated cylinders Boiling tube 36 Syringe Electronic balance 3 Dropper Timer Labels Thermometer Water bath Enzyme source egg. Radishes/celery Hydrogen peroxide Range of buffer solutions pH paper Washing up liquid Disposable gloves equipment’ – see Section 1 . Advance preparation Prepare buffer solutions. Obtain fresh celery.
Advance chemical preparation (a) Hydrogen peroxide (Prepares 250 ml of 1 MRS. Volvo’ solution) Wearing gloves, measure out 29 ml of ‘100 Volvo’ hydrogen peroxide into a measuring cylinder. Make up to 250 ml with water, add to a labeled bottle and mix well. Alternatively, small quantities of hydrogen peroxide can be purchased in the local pharmacy. Safety precautions Hydrogen peroxide is both oxidations and corrosive. For further information see MUMS. Expected outcome of experiment Catalane from celery has an optimum pH of 9.
This buffer solution should result in the greatest volume of foam produced. At pHs above and below 9 the activity of catalane decreases, less foam will be produced. Disposal and post-experiment work To dispose of hydrogen peroxide add small quantities (100 ml) in OIL of water and run to foul water drain. For the datelining method for this experiment, please see Section 3. Student Notes Apparatus required per group Weight boat 3 x Graduated cylinders 3 x Boiling tubes 3 x Labels Trough Celery Buffer solutions Washing-up liquid
Assembled apparatus Method 1 . Add 20 ml of one of the selected buffers too 100 ml graduated cylinder. 2. Using a dropper, add one drop of washing-up liquid to the cylinder. 3. Add 5 g of finely chopped celery to the cylinder. 4. Add 2 ml of hydrogen peroxide to a boiling tube.