enzyme lab (pH levels)

Purpose: To see the effects of varying pH on the enzyme activity and to find the optimal pH for catalase to work.

Procedure:

1. Dilute solutions of HCl and NaOH in different test tubes according to the table below, add 5 mL of H₂O_{2 to each test tube, swirl to mix}
2. _{Set up a water displacing station: fill a water trough and graduated cylinder with water (to the top), invert the graduated cylinder into the water trough carefully (do not let air in).  Place a beaker underneath the water trough to collect displaced water.}
3. Insert a rubber tube into the graduated cylinder that is connected to a rubber stopper (will be used to cover Erlenmeyer flask)
4. _{In an Erlenmeyer flask, add 5 pieces of filter paper (soaked in liver juice) to the bottom of the flask}
5. _{Add the first dilution into the flask, shake and cover the flask immediately, use a timer to record time needed for the reaction.}
6. _{Stop timer and record results when oxygen stops displacing water and when water stops overflowing from the water trough}
7. _{Repeat steps 2-6 for other dilutions}

Dilutions:

HCL	0ml	3ml	1ml
Water	0ml	2ml	4ml
time	39’	1:07’	1:45’
Amount water displaced	0 ml	0ml	5ml

NaOH		1ml	2ml	3ml	1ml *2nd trail
Water		4ml	3ml	2ml	4ml
time		2:10’	3:00’	2:40’	2:21’
Amount of displaced	gas	153ml	15ml	5ml	167ml
	water	115ml	11ml	2ml	220ml

lab partners: Ellen Zhou, Grace