Presentation on theme: "Unit 2 PPA3 The effect of changes in pH and temperature on the decomposition of hydrogen peroxide."— Presentation transcript:
Unit 2 PPA3 The effect of changes in pH and temperature on the decomposition of hydrogen peroxide
The effect of changes in pH and temperature on the decomposition of hydrogen peroxide (Unit 2 PPA 3) (1)When hydrogen peroxide decomposes it gives off oxygen gas. The rate is determined by counting the number of bubbles of gas given off in 1 minute. The aim of the experiment is to show the effect of changing temperature or pH on the enzyme catalysed decomposition of hydrogen peroxide. (1) Describe how the apparatus shown below is used to measure the rate of the enzyme catalysed decomposition of hydrogen peroxide. Side arm tube Potato discs Hydrogen peroxide Note:- the potato discs contain the enzyme catalase. (2) How can the effect of pH be investigated? (2) Buffer solutions of differing pH values (4, 7 and 10) are added to the hydrogen peroxide solution. (3) How can the effect of temperature be investigated? (3) The hydrogen peroxide solution is warmed by placing the side arm tube in a beaker of hot water until the desired temperature is reached. Then the potato discs are added.
(4) The enzyme’s activity is highest at a temperature of about 37 o C. At temperatures higher, or lower than this value the activity of the enzyme decreases sharply. Number of bubbles of gas (4) The graph shows the effect of temperature on the number of bubbles of oxygen gas given off in 1 minute. Describe how the activity of the enzyme is affected by changes in temperature. Temperature ( o c) 5 10 15 20