PAG 04: Enzyme-Controlled Reactions Flashcards
1
Q
Aim
A
Investigate the rate of enzyme-controlled reactions using catalase.
2
Q
Equipment
A
Equipment ● Hydrogen peroxide ● Syringe ● Distilled water ● Delivery tube ● Marker ● Trough ● Potato ● Cork borer ● Scalpel ● Stopwatch ● White tile ● Boiling tube rack ● Measuring cylinder ● Conical flask
3
Q
Method
A
- Label 5 boiling tubes: 100%, 80%, 60%, 40%, 20%
- Make a simple dilution of hydrogen peroxide according to the chart below.
- Set up the measuring cylinder, trough, delivery tube, and conical flask. Make sure the
measuring cylinder is full of water. - Using the cork borer, cut out 5 potato cylinders and trim to equal lengths of 50 mm. Make
sure that any potato skin is removed. - Drop one piece of potato into the conical flask containing 100% hydrogen peroxide. Make
sure the apparatus is airtight by fixing the bung firmly in place, and start timing immediately. - After 5 minutes, read off the measuring cylinder to record the volume of oxygen released in
5 minutes. Record in a table as seen below. - Calculate the rate of reaction using the formula:
rate of reaction (cm3 min-1) = volume of oxygen released (cm3 ) / 5 (min) - Rinse out the conical flask and repeat steps 1-7 with the other concentrations of hydrogen
peroxide. - Plot your results on a graph of ‘concentration of hydrogen peroxide’ against ‘rate of
reaction’. Pay attention to the shape of your resulting graph.
4
Q
Controlled variables
A
Controlled variables ● Temperature ● pH ● Time for gas collection ● Length of potato cylinder
5
Q
Risk assessment
A
Hydrogen peroxide is an irritant, wear safety goggles when handling and avoid contact with skin.
Take care when handling the sharp cork borer and scalpel.