Investigating an enzyme-controlled reaction: catalase and hydrogen peroxide concentration

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Investigating an enzyme-controlled reaction: catalase and hydrogen peroxide concentration

Date: 08/05/09

Aim:

To investigate the rate of oxygen production by the catalase in pureed potato as the concentration of hydrogen peroxide varies

Hypothesis:

I predict that as the concentration of hydrogen peroxide increases, the rate of reaction will increase until the pureed potato becomes saturated with the hydrogen peroxide. If the reaction reaches saturation point, no more reaction will be occurred.

The reason that the rate of reaction increases is that more substrates can react with more active sites of the enzyme when the concentration of hydrogen peroxide increases. As a result, the more oxygen will be produced in the high concentration of hydrogen peroxide.

10% of hydrogen peroxide will produce 10cm3 of oxygen from every cm3 that decomposes. In this procedure, 2 cm3 of 10% hydrogen peroxide will release 20cm3 of oxygen if the reaction goes to completion.

Variables

  • Independent:-The different concentration of hydrogen peroxide
  • Dependent:-The rate of reaction (the amount of oxygen produced)
  • Controls: - Standard Pressure and temperature of the room

- Measuring equipments are kept consistent

                  - The amount of pureed potato

                  - The constant temperature of hydrogen peroxide and potato

                 

Data Collection

Table 1: The amount of oxygen produced in the different concentration of hydrogen peroxide

Observation: As soon as the 2cm3 of hydrogen peroxide was added in the conical flask which contained the pureed potato, air bubbles begun to be produced and gathered in the measuring cylinder through the tube. There was no reaction in the distilled water but as the concentration of hydrogen peroxide increased, 5% to 25%, the more amount of oxygen was produced, 2.00mL to 5mL in the first trial. Also, the conical flask became warm as the reaction occurred. It indicated that heat was released and it meant that there was an exothermic reaction.

Data Processing

Table 2: The average amount of oxygen produced in the different concentration of hydrogen peroxide

Calculations

For the average amount of oxygen produced (2% of hydrogen peroxide)

=

=

= 1.80 ± 0.25mL

For the rate of reaction (2% of hydrogen peroxide)

=

=

= 0.06

Evaluation

QUESTIONS

  1. Apart from oxygen, what product is made when hydrogen peroxide breaks down?

Apart from oxygen, water is made when hydrogen peroxide breaks down.

2H2O2      2H2O + O2

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  1. Identify any anomalies or inconsistencies in your results.

Students may identify some anomalies or inconsistencies in their results. They should be able to explain what to do with them.

  1. Describe the shape of the graph.

At low concentrations, the graph will show an increasing rate of reaction as concentration increases, levelling off at higher concentrations.

  1. Explain the shape of the graph in relevant biological terms.

The shape is explained by the concentration of substrate directly affecting the rate of reaction until another limiting factor becomes more important.

  1. Describe any ...

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