Hypothesis 1: The rate at which the enzyme catalase breaks down hydrogen peroxide varies with time.
Investigation plan: In the reaction between hydrogen peroxide and catalase the rate of the decomposition of hydrogen peroxide can be measured by measuring the rate at which oxygen gas is given off.
2H₂O₂ 2H₂O + O₂
Variables:
Independent variable: Time
Dependent variable: Volume of oxygen
Controlled variables: Temperature, Ph, volume of hydrogen peroxide and volume of catalase.
Apparatus:
A manometer
Manometer fluid
1 boiling tube
10 ml H₂SO₄
Tongs
Test tube rack
A rules
Rubber tubing
A marker pen
A clamp
A stop clock
Two, 5ml syringe
A rubber bung
Method:
Clamp a boiling tube to a stand and carefully insert the manometer (with fluid into a rubber bung)
Using a syringe place 4cm3 of hydrogen peroxide solution into the boiling tube.
Using another syringe place 0.5cm3 of catalase into the boiling tube
Place the bung back into the boiling tube as quickly as possible.
Start the stopwatch and take the initial reading on the manometer and then take it again after 30 seconds.( final volume)
Use your final volume as your new initial volume and take the reading again after 60 seconds.
Continue taking the reading after every 30 seconds until the reaction stops.
Record your results in a clear table.
Plot a graph of volume of oxygen produced against time.( see diagram)
Results:
Hypothesis 2: The activity of enzyme catalase is affected by change in temperature.
Variables:
Independent: Temperature
Dependent: Volume of oxygen.
Controlled variables: Time, volume of catalase, volume of hydrogen peroxide and PH.
Apparatus:
A manometer
Manometer fluid
6 boiling tubes
30ml H₂SO₄
Tongs
Test tube rack
A ruler
Rubber tubing
A marker pen
A clamp
A stop clock
Two, 5ml syringe
A rubber bung
A thermometer
Method:
Set up a thermostatically controlled water bath at 30oC.
Label six boiling tubes 1-6.
Use a syringe to measure out 4cm3 of hydrogen peroxide into boiling tube 1.
Use another syringe to measure 0.5cm3 of catalase into another test tube.
Place both tubes in the water bath for 30 seconds.
Add the catalase to the hydrogen peroxide and place a rubber bung with a manometer inserted as quickly as possible
Immediately start a stop clock and take the initial manometer reading.
Measure the volume of the liquid in the manometer after 30 seconds (final volume).
Repeat using the same volumes of hydrogen peroxide and catalase but place in water baths heated to 40 degrees Celsius, repeat at 50 degrees Celsius and 60 degrees Celsius.
Each time measure the final volume of the liquid in the manometer after 30 seconds.
Record your results in a clear table.
Plot a graph of temperature against the volume of oxygen.
Results:
